The firefighters, Rescue Squad and paramedics of Chicago Firehouse 51 risk their lives week in and week out to save and protect the citizens of their incredible city.This is an extended family and everyone inside Firehouse 51 knows no other way than to lay it all on the line for each other.
The sixth season opens with most of the squad still trapped inside the burning warehouse fire. Chief Boden makes a risky last-minute decision in an effort to save his men. Dawson continues to deal with her father, who has new plans for himself. Brett's childhood friend Hope visits the Windy City and strikes the attention of someone within the firehouse, while Kidd goes head-to-head with her landlord. Meanwhile, a fire at a high school hits close to home for Boden.
After learning the school fire wasn't an accident, Chief Boden turns up the pressure on Severide and Casey to investigate the cause of the fire that trapped his wife. Fueled by a competitive bet against Firehouse 87, Mouch pushes all of the wrong buttons in his need to win the competitive challenge known as the firefighter muster. Meanwhile, as Kidd settles into her new living arrangement, her unresolved feelings prompt her to question the intentions of newcomer Hope.
Lt. Casey gets off on the wrong foot with Sam Mullins, a temporary Chief who is filling in for Boden at House 51 for the morning. When Casey later makes a risky move in an attempt to save a distraught man from jumping off a building, Mullins has a surprise that Casey does not expect. Mouch flies in Cruz's brother Leon as a birthday surprise, but the rest of the squad struggles to keep it a secret. Meanwhile, Brett is caught off guard when she learns new information about her hometown friend Hope.
Severide and Stella search for Grant, who's AWOL from Chicago Med. Dawson questions her career path. Casey's relationship with his political consultant cools. Borrelli's anger at Boden over his brother's death boils over. Mouch and Brett partner on a new venture.
Casey and Dawson find themselves in the midst a potential political mess. Stella has to make a big decision about her ex-beau. The squad responds to an auto accident. Severide befriends a socialite. Brett and Mouch set aside their writing differences for the greater good.
Casey seeks help with a personal matter from Susan Weller. A rich party guy wants Severide to travel with him. Stella tries to help a sick street kid. Otis and Herrmann share their concerns about Molly's lack of customers.
Lt. Casey finds himself in a bad spot when a forklift accidentally pierces a tank storing acid. Casey is forced to use extreme measures to help a father and daughter in peril. Dawson and Brett respond to an elderly woman who has a difficult senior advocate. Mouch and Brett continue with their secret project, and Otis shares some exciting news as he prepares himself for an unusual expedition.
Lt. Casey is unable to rescue a woman who becomes trapped inside her burning greystone, prompting him and Lt. Severide to butt heads over the husband's role in the tragedy. Herrmann is on a mission to catch a mystery tagger that keeps targeting their firehouse and Boden gets a surprise visitor. Meanwhile, Dawson and Brett respond to a 16-year-old boy who was injured during a romantic homecoming proposal.
While responding to a call in the field, Dawson accidentally hits a pedestrian who stepped in front of the ambulance, and is left to deal with the repercussions. Lt. Casey and Lt. Severide disagree and continue to investigate an arson case while Chief Boden is left to decide whether to attend an important function in New York. Elsewhere, in hopes of preparing him for a possible promotion, Lt. Casey puts Herrmann at the helm for a shift so he can discover firsthand what his superiors deal with.
It's a family reunion when Dawson and Antonio's mother and father come to Chicago for their big anniversary party, but things quickly turn south. When a deep secret comes to the surface involving his stepson James, Chief Boden decides to take matters into his own hands. Meanwhile, Casey tries to save a young boy during a harrowing call to a warehouse and Otis and Kidd become competitive at the mud-hundred race.
Lt. Casey and Dawson apply for permanent adoption of Louie, but quickly discover a hurdle. Firefighter-turned-medical student Jeff Clarke approaches Lt. Severide with an interesting proposition. With hopes of reinvigorating business at the bar, Otis convinces a skeptical Herrmann to throw a bash in celebration of the milestone 100th anniversary of Molly's, but not without complications.
Dawson and Casey deal with legal matters in hopes of remaining Louie's legal guardians. Severide continues in his efforts for a bone marrow procedure to help Anna, but when things don't go as planned, he finds himself slipping back into old habits. Meanwhile, Brett opens up to Dawson, and members of Firehouse 51 become competitive, much to the dismay of Chief Boden.
Severide agrees to a bone marrow donation but a work accident throws everything into flux. Casey and Dawson try to find harmony at home. Meanwhile, Otis and Mouch decide to film a PSA encouraging people to join the Chicago Fire Department but hit a creative wall in the process.
Dawson finds it hard to keep her emotions in check during an ambo run involving a pregnant teen. Elsewhere, the firehouse is called to the site of a building fire and Casey is forced to make a split-second decision when two victims are each in need of life-saving assistance. In the aftermath, Casey is left to deal with the repercussions. Meanwhile, Severide shares a bond with Anna, as she makes her recovery.
The team is on high alert when a previous incident during a fire call leaves a dangerous man on the loose with a vendetta to target Lt. Casey and Firehouse 51, and prompts CPD to step in. Dennis Mack, a buddy firefighter of Severide's father, comes to town to shadow the squad but may have ulterior motives. Meanwhile, Brett and Antonio's relationship hits some bumps in the road when his ex-wife Laura surfaces and Casey has a present for Dawson.
When truck and squad are summoned to the scene of a dangerous accident, Chief Boden makes a split-second decision that overrides Chief Anderson, the incident commander whose house was the first to respond to the call. Feeling his authority was undercut and his reputation damaged, Anderson uses his power to make things miserable for Boden and all of House 51 feels the repercussions. Meanwhile, Severide contemplates a major life-changing decision, Herrmann does a good deed and Brett looks to make some personal changes to herself.
After exercising his disdain and authority over Chief Boden, Chief Anderson reassigns members of 51 to various houses around town, citing the need for improvement. The ramifications are felt by the crew, who are left to make the best of their respective situations in their new surroundings. Boden fights to repair the situation, but it just might be out of his control. Elsewhere, Severide toils over an important decision.
Truck and squad are called to aid in a massive all-city response when an old, ill-equipped factory-turned live/work space quickly turns into a firestorm, trapping countless unsuspecting victims. The dire situation quickly turns personal when it is discovered that one of Chicago PD's own has a family member at the scene. With the rescued victims in need of serious medical attention, the doctors and nurses of Chicago Med are tested as the major influx of patients are brought through their doors. Meanwhile, in the aftermath, the building owner steps forward to cooperate with the ongoing investigation, but the situation takes a sudden and unexpected turn.
When a turf war escalates, members of truck and squad find themselves caught in the middle as unsuspecting hostages when a group of armed gang members take cover and assume control over Firehouse 51. The situation turns even more dire when one of the infiltrators is wounded and in need of serious help.
When similar car accidents uncover the fact that someone may be targeting innocent people, a determined Dawson takes matters into her own hands to help push things along. Severide does everything he can to make Anna feel welcome in her new Chicago surroundings. Herrmann, Kidd and Dawson decide to have Molly's included as a stop in this year's pub crawl, despite strong concerns from Otis, who may have his own reasons for standing alone. Meanwhile, Casey tends to his Alderman's duties when a persistent constituent asks for his help in resolving an issue.
Casey discovers a new crack house on the block that is harboring a female junkie and goes to extreme measures to remedy the situation. Dawson and Brett get assigned a new trainee for the shift and the newbie gets the two in trouble when he surprises them during a harrowing call. Meanwhile, Severide gets an unexpected visit from his father, Benny, and Herrmann deals with family issues when his son Lee Henry gets into trouble at school.
When the squad's rig breaks down in the field, Casey reunites with his old friend and colleague Jason Kannell from Squad 6, whose crew gets assigned a temporary change of quarters until the rig issue is resolved. Dawson and Brett serve their time in retraining, both tackling the class in unique ways. Severide tries to remedy what is going on with Anna and finds support from unlikely sources. As Connie returns from her family engagement, the crew lays bets on how long her temporary replacement Marcy will last.
Casey goes to drastic measures to help his friend Kannell. Lt. Severide helps an old widow come to terms with letting go, but realizes he may be the one needing help. Otis and Cruz deal with surprises when they find a new roommate to move in. Dawson and Brett get crafty to save a young girl.
Cruz finds himself in a bad spot when an off-duty incident begins to unravel, prompting Mouch to step in and offer help in hopes of avoiding serious consequences from the CFD. Casey goes head to head with a big politician to get his measure for first responders passed. Lt. Severide makes life difficult for newest team member Jason Kannell and Dawson gets an unexpected visit from her father.
A dangerous warehouse fire puts truck and squad at risk. Tensions are high for Dawson and Casey when Dawson's father overstays his welcome at their home. Meanwhile, Casey continues to fight for his first responders bill, Mouch makes a serious decision regarding his future and Herrmann goes to tremendous lengths to make a young boy smile.
Boden offers to host a wedding at the firehouse after a fire destroys the original location, but it doesn't sit well with Chief Riddle, who also butts heads with Dawson over her ability to perform. Severide fights for his old position. Capt. Patterson finds himself torn between leadership and his colleagues.
Boden's new neighbor asks him for a favor that could have serious repercussions. Severide is upset when he's treated like a candidate by Patterson. Cruz is visited by a gangbanger who knows his brother. The team responds to a call that involves an 18-wheeler; and is thanked with tickets to see Rush.
Boden suspects his neighbor is setting him up; Severide, who's still on probation, receives a surprise visit from his father and also learns something about Patterson that could be a game changer. Romance blossoms at a fire department gala.
Boden believes Maddox is behind Serena's accusations. Severide reaches out to Jamie, who's Maddox's lawyer, in an attempt to help. Patterson questions whether Boden can remain chief. Brett and Chili suspect that a man passed out in a garden is connected to a previous call. Otis has problems with his social calendar.
Patterson fills in for Boden, who's trying to clear his name. Severide learns where Serena may be hiding. Herrmann and Otis give Freddie a job that keeps him close by. Jimmy and Chili draw more attention then either bargained for.
Members of Firehouse 51 band together and anxiously await word at Chicago Med when one of their own falls victim to a life-threatening stabbing. Cruz urgently works with members of Chicago P.D. to track down Freddie's whereabouts when he goes missing. Dr. Choi and Dr. Halstead tend to an attempted suicide victim whose condition raises some eyebrows. Meanwhile, Mouch surprises Trudy and Chili's odd behavior has Brett and Jimmy worried. (Malignant (2) aired on Chicago Med, season 1, episode 5. Now I'm God (3) aired on Chicago P.D., season 3, episode 10.)
A tornado threatens Chicago. Chili makes a major mistake, which causes Brett to report her to Boden. Otis asks Dawson to help him solve his women troubles. Severide assists a Department of Homeland Security agent.
Freddie's father begs Herrmann to forgive his son's assault. Casey discovers that a makeshift shelter housing people displaced by the tornado may close. Casey attends a fund-raiser at the request of an alderman. Dawson and Brett experience repercussions after telling Boden about Chili's erratic behavior.
The team responds to a mass shooting; Casey investigates the missing money from the fund-raiser. Jimmy agrees to represent the firehouse in a boxing match against the Chicago PD's 21st District. Chili's behavior continues to be an issue for Brett.
Severide confronts Chili about her erratic behavior. Members of the firehouse rally around Casey, who they think would make a great candidate for alderman. Jimmy squares off against Antonio in the first annual "Battle of the Badges" boxing match.
The team responds to a suspicious call from a neighboring firehouse; and welcomes a new firefighter, though her addition has repercussions. Casey moves forward in his run for alderman.
Casey reconsiders his run for alderman after he's targeted by a propaganda campaign. The squad responds when a man is trapped inside of a burning car. Trudy's nerdy brother plans Mouch's bachelor party. Jimmy and Brett investigate a kidnapping on their own.
Severide and Cruz find a child's remains inside a chimney while investigating a possible carbon monoxide leak inside a home. In other events, Casey braces for the worst in his run for alderman while Alderman Becks continues to bad mouth him to the press.
Sylvie witnesses a murder and is threatened by the shooter not to go to the police. Firehouse 51 jumps into action when a fire breaks out at a restaurant and traps several people inside a vault. Mouch starts to get cold feet.
When a high school student becomes an innocent victim of a gang retribution incident, a very determined Lt. Casey tries all means necessary to resolve the issue. Severide lends a hand to Detective Holloway, who is working a dangerous undercover investigation, and watches over her 9-year-old son at the firehouse. Brett and Jimmy are called to aid a woman who takes a fond liking to Jimmy. Meanwhile, Otis makes a surprising discovery that leaves him very concerned and Herrmann goes toe-to-toe with Stella to claim bragging rights over who can best run a bar.
Firehouse 51 unites to help a young boy in tragic circumstances. A high-powered political consultant helps Casey navigate a potential scandal. Cruz makes a mistake that nearly costs him his life.
Dawson saves a young boy from an apartment fire. Kidd's idea for Molly's doesn't go as hoped. Severide hits a wall while advocating for new fire masks. Cruz and Brett utilize a secret weapon to get Otis to see Dr. Halstead take a blood test.
The team responds to a building collapse that's trapped more than a dozen people. Dawson's quest to foster Louie is aided by a familiar face. Otis, who's on medical leave, meets his temporary replacement. Severide and Kidd continue to see each other. Casey is at odds with Antonio.
In the Season 4 finale, Boden and Jimmy are at odds. Kidd deals with her unstable ex. Dawson continues her quest to foster Louie. Casey's new political consultant urges him to think big. The team responds to a dangerous structure fire.
The squad members come together to support one of their own. Herrmann tries to figure out how to reopen Molly's after it gets shut down. Severide digs deep into the arson investigation.
Evidence that seems to exonerate Boden may not be enough. Brett and Chili find themselves in a precarious situation. The team responds to a stuck elevator in a hotel. Jimmy Borrelli's older brother wants him transferred to a different house.
Boden's job is on the line pending an internal investigation. Severide adjusts to Patterson, his new commanding officer. Dawson shakes things up at the work. Casey searches for important evidence in his investigation of Nesbitt. Herrmann tries to keep the peace with Molly's new neighbors.
Casey is placed in a dangerous situation while working undercover to bring down a trafficking ring being run out of Nesbitt's club. The squad's high turnover rate results in an unwelcome surprise for Severide. Dawson recognizes that her life is about to change. A new candidate makes an unusual first impression. Residents band together to protest a drug den in their neighborhood.
Lt. Casey puts his life on the line and digs deeper into the shady dealings of Jack Nesbitt. Chief Boden must figure out how to create unity in a divided house, while Severide comes to question his own judgment. A dangerous warehouse blaze quickly gets out of control and threatens members of firehouse 51.
At Sgt. Voight's urging, a determined Lt. Casey agrees to go undercover in an effort to provide proof of Jack Nesbitt's shady dealings. Meanwhile, Otis and Severide continue to disagree about the integrity of Scott Rice, causing tensions to flare between members of truck and squad. Meanwhile, Herrmann helps out a fellow member of the firehouse.
Boden forces members of Firehouse 51 to pull themselves back together in the aftermath of a harrowing fire explosion. While Severide goes missing for one week too many, Casey works to track down his whereabouts. Newhouse brings some unexpected news regarding one of Mills’ relatives. Herrmann and Otis make some new goals regarding Molly’s.
Severide returns to Firehouse 51, but he is clearly not his usual self. Dawson counts down the weeks until she gets started as a candidate at the Austin Firehouse. Mills learns more about his father’s family. Herrmann asks the rest of the Molly investors to come up with some new ideas to turn the business around.
The members of Firehouse 51 and the Austin firehouse clash when trucks collide on the way to a call. Boden comes up with a plan to get Dawson her badge. Mills faces his past and future. The Molly's group hits a speed bump starting the food truck.
Dawson tries to strike a balance with Casey during her first day as a candidate. Mills ponders an uncertain future. Severide faces his demons. A city inspector visits Molly's.
Casey deals with the aftereffects of his sister's divorce announcement. Dawson and Mills get used to their new roles at Station 51. Brett ponders whether to leave Chicago. The Molly's crew works to get the food truck started.
Casey comes to the aid of his sister Christie and faces down his corrupt brother-in-law, while Brett goes above and beyond for a mother in need. Elsewhere, Mills gets educated on the exciting world of unlicensed private investigation and Dawson begins training with Herrmann.
In part one of the crossover with Law & Order: SVU and Chicago P.D., Severide returns from Vegas with a huge surprise that sends ripples through Firehouse 51. Mills wonders if the dangers of Newhouses' off-duty gig are worth the cash returns, while Molly's II is in dire need of a good chef. Members of Firehouse 51 are forced to contend with a house fire, but when the injured owner is rescued from his cellar clutching a suspicious box, Severide brings in Sergeant Voight and Detective Lindsay into the mix for further investigating. (Chicago Crossover (2) aired on Law & Order: Special Victims Unit, season 16, episode 7. They'll Have to Go Through Me (3) aired on Chicago P.D., season 2, episode 7.)
When a massive helicopter explosion in a densely populated area leaves a trail of debris scattered across a full city block, members of the firehouse spring into action as lives hang in the balance. Squad 3 finds itself in a precarious position, Brett is cornered by a dangerous man in the midst of the madness and Dawson is shocked to discover what actually brought the chopper down.
When the team responds to a semi-truck leaking hydrochloric acid in a busy intersection, Casey and Dawson find their relationship being put to the test. Meanwhile, Severide learns more about Brittany’s past and Mouch has some difficulties in his dating life.
A house fire leads members of the truck and squad to race to save the lives of the couple trapped inside, and then are faced with the perplexing aftermath. Meanwhile, Chief Boden prepares to start his new family, while the combination of life at work and home pushes Casey and Dawson apart. Elsewhere Molly’s II has its chance to shine at the Chicago Holiday Fest.
The firehouse receives unsettling news when two of their own come up missing following a routine call, prompting members of Chicago P.D. to lead the search. Meanwhile, Casey and Dawson have a hard time figuring how to juggle their personal and professional lives. Elsewhere, Chief Boden and Donna struggle with news that their newborn has potential complications and they receive a surprise out-of-town visitor.
Severide and Dawson discover startling evidence found at a storage unit fire that appears connected to the fire that took Shay's life. Meanwhile, the firehouse bands together when Chaplain Orlovsky is the victim of a bad car accident. Elsewhere, Chief Boden's father visits, but quickly wears out his welcome with his unsolicited parenting advice.
More clues surface surrounding the fire that killed Shay, leading Severide to a most unexpected source who may be able to provide pertinent information. Shay’s sister comes to town, prompting members of the firehouse to remember Shay’s life. Cruz is in for a surprise when Otis’ grandmother moves into their apartment. Boden finds a way to help his dying father make the most of his last few weeks. (A Little Devil Complex (2) aired on Chicago P.D., season 2, episode 13.)
Mills and Brett race to recover a missing teenager and are left stranded in the unforgiving elements, while the rest of Firehouse 51 babysits an abandoned newborn. Severide receives an interesting job proposal. Boden finds himself at odds with his father over his treatment and the planning of a big party in his honor.
A temporary chief fills in for Boden, who is forced to take some time off for personal reasons.
The interim chief makes a tactical error during an apartment fire, stirring up tensions and putting careers in jeopardy. Meanwhile, Mouch discovers that his donation to a fertility clinic has resulted in a child, and Dawson goes out on a double date with Brett and Cruz.
Severide lobbies Chief Boden for a favor for Scott Rice, an old friend needing a second chance with the CFD, but Casey and Otis have their doubts. Elsewhere, Mills works to regain his active squad status while Brett and Dawson decide they need a big night out.
Herrmann tries to rescue a toddler from a structure fire. Mills discovers unexpected news.
The Chicago fire team works seamlessly with Chicago Med personnel to help aid victims of a deadly gas leak, but things quickly take a turn for the worse when the hospital is suddenly forced into quarantine.
Truck and squad are called to the scene of a car crash that has Mills desperately working to save the life of a driver seriously injured in the wreck. Meanwhile, Casey has some doubts about Jack Nesbitt, whose strip club he is remodeling on the side. Elsewhere, Hermann, Otis, Cruz and Chaplain Orlovsky help get their team ready for the peewee hockey championship, but Herrmann might prove more of an obstacle than the other team.
An apartment fire linked to a case of rape and attempted murder calls for members of the CPD to team with the Special Victims Unit, which had a similar unresolved case that has eluded them for more than 10 years. This prompts Sgt. Benson to come in from New York to assist with the investigation in which she is all too familiar. Meanwhile, doubts among the squad towards one of their own causes Severide to lay down the law and Dawson puts her life on the line during a call. (The Number of Rats (2) aired on Chicago P.D., season 2, episode 20. Daydream Believer (3) aired on Law & Order: Special Victims Unit, season 16, episode 20.)
When a fire claims one of their own, there's plenty of guilt and blame to go around. Lt. Matthew Casey, in charge of the Truck, tries to carry on, but butts heads with the brash Lt. Kelly Severide of the Rescue Squad - and each blames the other for their fallen team member. The firehouse also includes: Battalion Chief Wallace Boden, a fireman's fireman who is confronted by important personal decisions; paramedics Gabriela Dawson and Leslie Shay, who share a close bond and team together to face some of the most harrowing situations imaginable; Peter Mills, an academy graduate who is the latest generation in a family of firefighters; and Christopher Herrmann, a seasoned veteran who loses his home to foreclosure and now must uproot his family to move in with his in-laws.
Severide is hiding a serious shoulder injury sustained in the fire that killed Andy Darden, and grapples with his guilt as he fights to rescue a construction worker trapped in a building collapse. Adding to the burden, Darden's wife Heather turns on Severide at the annual firefighters' barbecue, blaming him for her husband's death. A call is made to an accident site at Hancock Tower, where two teenagers are pinned in a vehicle trapped beneath the falling debris of a broken window washer's cart. Meanwhile, Casey and Hallie work to figure out their future together.
Casey faces pressure to cover for a cop's son, who was responsible for a drunken-driving accident that left a teenager paralyzed. Meanwhile, Severide ignores his doctor's warnings that his neck injury may never heal if he doesn't seek treatment; and Mills must choose between working at the fire department full-time or helping his mom with her restaurant.
Chief Boden is accused of leaving a homeless man to die in a warehouse fire after ordering his men to evacuate the scene, creating negative press and bad feeling within the department. Meanwhile, Lieutenant Severide helps an elderly woman facing some neighborhood problems. Detective Voight ramps up his intimidation tactics aimed at Casey in an attempt to discourage him from testifying against his son. Shay is forced to revisit her heartbreak over her ex-girlfriend Clarice, when she finds herself face-to-face with the ex and her husband during a call. Hermann’s temper flares during a rescue call at a Halloween block party.
Casey confronts Detective Voight about his harassing tactics, vowing never to back down, and ends up paying the price for his decision. Dawson faces disciplinary action for her on-the-job conduct. Meanwhile, Severide finds his arm failing him during a rescue at a construction accident, and reaches out to Anna, an old flame and pharmaceutical rep, hoping she might be able to help alleviate his injury problems.
Facing suspension, Dawson gets a hand from the same girl she saved through the procedures that landed her in front of the disciplinary board. Lieutenant Casey finds his fuse shortening as Detective Voight stops at nothing to get him to retract his statement. However, when Casey lays his life on the line during an apartment fire, he may have unknowingly caught the break he was needing.
Everyone in the firehouse is ordered to take a drug test after a call to a daycare center exposes them to a makeshift meth lab, and Severide stalls, not wanting his injury, or the painkillers he takes, to be discovered. Meanwhile, Truck and Squad find themselves pinned down by gunfire while trying to help the victim of a gang shooting, and a deep-fried turkey fire grows from small to explosive when a garage catches fire. Elsewhere, Dawson saves a bleeding man and Casey delivers a baby on the scene of a massive car pileup on the freeway.
At the site of a train accident, Peter Mills becomes deeply upset when he observes the dead body of a young victim. Unable to shake his emotional distress about the event, he questions his future as a firefighter. Dawson and Shay save a 6-year-old girl whose mother is abusing her – but their confrontation leads the woman to resort to dire actions. Meanwhile, Severide aggravates his injury while rescuing a heart attack victim and Shay sends Clarice, her married, pregnant ex-girlfriend, back home to her husband.
After he's injured in a terrible fire at an auto machine shop, Jose Vargas is forced to go on disability and leave his life as a firefighter behind - a task he finds incredibly difficult. Chief Boden tries to help a suspected teenage firebug. Also, Severide receives an enticing invitation from Renee, a woman who he saved from a car crash incident involving live electrical wires. Meanwhile, Cruz tries to save his younger brother Leon from the gang he is involved with.
After putting out a kitchen fire in an upscale townhouse, Casey, Herrmann, Mouch, Cruz, Otis and Mills find themselves accused of stealing a $50,000 diamond necklace from the home, touching off an internal investigation. Cruz’s brother Leon is caught in the middle of an escalating gang war, leaving Cruz to make a desperate choice to save him. Meanwhile, Dawson invites Casey to her cousin’s fancy Christmas party, and a frustrated Shay has reached her limit with Severide.
Eaten up by his guilt over Flaco’s death in the fire, Cruz goes to Casey to confess. While Shay recovers from a head injury sustained in the ambulance crash, Severide asks Dawson for her help in dealing with his own injury. Casey is caught in the middle of a family conflict between his mother and sister. Elsewhere, Herrmann finds a business deal hard to stomach.
Severide finally addresses Chief Boden about his injury and makes some important personal decisions about his future. Meanwhile, Casey struggles with family matters and Dawson takes matters into her own hands when she discovers a young girl who is the sole survivor at the scene of a rescue call.
A troubled Chief Boden goes to the police when a man dies in a hardware store fire set by Ernie, the troubled teenage firebug he’s been trying to help, and his Uncle Ray. Meanwhile, Severide decides on his future and reaches out to his father. Elsewhere, Otis finds camaraderie when he fills in for a few shifts at the slowest firehouse in the city, and makes a decision of his own, while Dawson and Shay find themselves in a bad predicament during a call to a tenement.
Severide finds that he shares a familiar past with Eric Whaley, the Lieutenant who was brought into the firehouse to help out. Dawson lets Shay in on her secret, while Casey deals with family issues. Meanwhile, a bad batch of heroin on the streets has Boden and the team scrambling, while Clarice and Shay find they have a new problem to overcome.
Dawson attempts to help her brother Antonio unravel the details of his drugs-and-gang investigation, and goes behind his back in turning to an unlikely source for assistance. Casey and his mother, Nancy struggle with their new relationship. Meanwhile, as a favor to Lieutenant Whaley, Severide visits someone important from his past, while Herrmann and Otis learn some hard truths about their "silent partner" in the bar.
The anguish that haunts Cruz over his previous actions boils over, as he puts himself and his fellow firefighters in jeopardy. Casey and his sister Christie try to solve their issues with their mother and each other. Meanwhile, Severide reaches out again to an important person from his past as a favor to Lieutenant Whaley and the squad gains new perspective after assisting the bomb squad on an extremely dangerous call.
Old emotional wounds are opened when Lieutenant Severide’s father Bennie comes to town and clashes with Chief Boden over the death of their former colleague. Mills helps a distraught driver who caused an accident and Shay makes a decision about her future with Clarice. Meanwhile, Herrmann, Otis and Dawson get to the bottom of a mystery about their bar.
With tensions still running high between Chief Boden and Bennie Severide, things boil over when Mills confronts Bennie about the fire that killed his father. Meanwhile, Severide, Casey and Bennie uncover the truth behind two mysterious diner fires and Shay takes a new direction with her plan to have a baby.
Accused of sexual misconduct by a former paramedic candidate, Severide faces potentially dire consequences and fights for his survival both within the Chicago Fire Department and the legal system. Detective Voight returns, looking to collect on the favor that Dawson owes him for helping her brother, Antonio. Casey falls back into old patterns in his personal life, while Dawson, Herrmann and Otis become the proud owners of a real neighborhood bar as Molly's prepares for its grand opening.
A frustrated Severide, turns to an unlikely ally to resolve his current dilemma. Casey begins to find satisfaction in his personal life, while Mills and Dawson face personal challenges. Meanwhile, the squad is called to the scene of a harrowing apartment building collapse.
Events force Lieutenant Casey to team up with the Intelligence Unit, now run by Voight, who doesn’t appear to have changed his crooked ways after his stint in prison. Shay's excitement at the prospect of becoming a parent grows, while Mills and Dawson face some personal challenges. Meanwhile, the house comes together to support the opening of Molly's.
When a call comes in from the Cook County jail, the squad steps into a volatile predicament and are tasked with trying to defuse an escalating situation. Shay remains hopeful about her baby dreams and Hermann's wife Cindy goes into labor with their fifth child. Meanwhile, Mills and Dawson face key decisions in their personal lives.
An arsonist targets Lt. Severide. Meanwhile, Station 51 is under scrutiny by Gail McLeod, a financial consultant for the city who is deciding if any firehouses should be closed. Mouch receives a visit from his Japanese girlfriend, Lt. Casey "celebrates the one-year anniversary of Andy's death, and Shay suspects Severide's paternity.
In the wake of Heather's incident, Lt. Casey is having a hard time handling his newfound responsibilities. Lt. Severide is on edge dreading the next attack from the firehouse's arsonist. Meanwhile, with Renee back from her mother's, Severide knows he has to confront her about his paternity suspicions. Elsewhere, Mouch begins his campaign for union president and Shay and Dawson feel that they need to get out more.
Lt. Severide has his strong ideas on who the serial arsonist is, but first needs to find proof to back up his suspicions. Meanwhile, Lt. Casey adjusts to his new lifestyle in the wake of recent events and Molly's bar is failing, much to the dismay of owners Hermann, Dawson and Otis. Elsewhere, Dawson goes out on a date with Jay Halstead, one of the bar regulars, and Mouch's campaign trail starts to get on track with the aid of Isabella, an old friend of Dawson's.
Lieutenant Severide is anxious to implicate the serial arsonist, while Dawson and Shay get a shock on a routine call. Meanwhile, suspicions continue to point to Clarke as the mole inside the firehouse and Molly's falls deeper into the red. Elsewhere, Mouch campaigns for union president, with the aid of Isabella, and Boden butts heads with Gail McLeod.
Boden's future with Firehouse 51 is on the line and McLeod keeps on him about his past wrongdoings, pushing him toward an early retirement. With Boden considering his options, McLeod calls on an unlikely candidate to potentially replace him as Chief. Meanwhile, it becomes clearer who the mole inside the firehouse is and everyone takes measures to make their disdain for him known. Meanwhile, Shay's social life is in full bloom and Arthur continues to take money from the struggling Molly's.
While out on a jog, Severide comes across a secluded and empty construction site and encounters a young boy who has been trapped in a backhoe loader and is in dire need of assistance. Boden and McLeod continue to butt heads about the future of the firehouse and Boden breaks news about his future to Casey. Meanwhile, it's election day for the union presidency and Mouch and Greg Sullivan have a debate on Otis' podcast. With rival bar Game Day's future in peril, the finger is being pointed at Molly's.
When a tanker collides into a commuter train that subsequently crashes into a warehouse, the firehouse is called to the horrific scene that tests everyone to the limits as life and death hangs in the balance. With the ultimatum in place for him or the firehouse, Boden is tasked with making life-changing decisions regarding his future. Severide learns more about Katie, the young woman he saw with his father. Meanwhile, Shay and Dawson are still at odds and Casey’s responsibility of being a surrogate father takes a sharp turn.
When the shooting of a young girl happens in their neighborhood, Cruz and his brother, Leon are forced to think about the gang they have tried to escape. The battle between Chief Boden and McLeod continues to escalate and Isabella convinces Mills to dress up for a fancy gala. Meanwhile, Lt. Casey is sad Dawson won't be coming by as much now that his parental duties are over, Shay is fed up with the firehouse and digs in deeper with Devon and Zoya's visa is expiring, prompting her to come up with an idea.
Chief Boden prepares to counterattack McLeod in a final effort to save the firehouse from closure and the romance between Dawson and Casey escalates. Leon is making progress in the gang murder investigation, but Cruz cannot stand being left in the dark by Voight, fearing for his brother's safety. Meanwhile, Severide and Katie bond to make up for lost time and Otis feels uncomfortable living with Severide and Shay after Devon's latest escapade.
Lt. Casey returns to work at Firehouse 51 after nearly being killed in a building collapse and Shay meets Allison Rafferty, her new partner, who is friendly to everyone except her. Dawson begins her rigorous training at the Chicago Fire Academy, while Lt. Severide prepares for his stint as instructor. Meanwhile, Clarke stubbornly does not speak with the police about the murder in which he is the prime suspect and the future of Molly’s looks bleaker than ever.
Lieutenant Casey tries to convince himself and everyone around him that he is one hundred percent healthy following his near-death incident in the line of duty. Shay, not wanting to delve into the emotionally traumatic incident, continues to elude a lawyer who wants to speak with her about Daryl’s suicide. Meanwhile, Otis and Katie bond over board games, Boden helps out a woman with a negligent landlord and Dawson notices fellow recruit Rebecca Jones undertaking some interesting test-taking techniques at the Academy.
When a drunk driver knocks down a transformer, the entire neighborhood is left without power on a frigid Chicago night and members of Firehouse 51 step up to lend their much needed help. While many from the community ride out the night at the station, in the midst of such close quarters, romances speed up and tempers flare. Meanwhile, Casey continues to lie to both himself and Dawson about his condition and the stakeholders in Molly's bicker about the bar's direction.
Severide feels sidelined as he leaves Detective Lindsay and the Intelligence Unit to do their job and locate his sister Katie. Shay gets an unusual tip from Chicago Blackhawk players Brent Seabrook and Duncan Keith, who makes friends with Clarke and stop by Molly’s. Meanwhile, Casey learns more about his head injuries after another close call and Dawson pushes hard to pass the physical test at the Academy.
Severide is getting impatient with the police as Vince Keeler walks free. Meanwhile, the house pulls out all the stops to save a girl trapped inside a donation bin, Mouch learns that Boden’s secretary Connie is not someone to mess with and the squad and truck are called to a serious high rise fire inside a 20-story downtown office building.
Lt. Severide hits the top of the list as Det. Lindsay starts calling in suspects with the clearest motives to make the guy who kidnapped Katie disappear. Meanwhile, Jones is still having trouble fitting in as word of her disruptions reach the fire department’s headquarters. Elsewhere, Herrmann celebrates his twentieth anniversary with his wife, but no one supports his idea on the gift he intends to give.
Lt. Severide is reminded of his own past by a man he saves from a car accident and feels compelled to help him. Elsewhere, Lt. Casey and Chief Boden grapple with how to dock Jones per her father’s orders. Meanwhile, Mouch and Dawson have troubles with the opposite sex and an emotional call to duty creates ripples throughout Firehouse 51.
Lt. Severide sticks his neck out for Dave Bloom, a fellow firefighter from Denver who is troubled by addiction. Elsewhere, Dawson and Shay leave town for a "girl's weekend" at a cabin in the woods. Meanwhile Jones struggles with the knowledge that her father is pressuring Chief Boden about her career path and Mouch's internet dating profile gets an upgrade with the help of Mills and the guys.
A suicide note is delivered to a surprised Dawson and Lt. Severide digs deeper into Bloom’s dark past. Elsewhere, Chief Boden learns shocking news, and with the help of Shay, Lt. Casey goes on the search for a life-changing item.
Lt. Casey and Dawson volunteer to help at a charity run at Chicago Medical when a massive explosion sends Chicago into chaos. With one of their own missing in the blast, the firehouse is tested like never before. (8:30 PM (2) aired on Chicago P.D., season 1, episode 12.)
With everyone’s support, Dawson makes final preparations to retake the fireman’s exam, but a call to the field may throw a major wrench into her plans. Elsewhere, Lt. Casey has an important matter to discuss with Antonio. Meanwhile, Lt. Severide and the firehouse welcome Rick Newhouse , the latest addition to the squad, Shay gets an uninvited surprise guest and Chief Boden makes a bold move.
A fire at a boarding school leaves Lt. Severide shaken and wondering if he could have done more. Meanwhile, with the firehouse in full support of Dawson as she retakes the fireman’s exam, Lt. Casey attempts some political maneuverings on her behalf. Elsewhere, Mills looks for answers about his father’s mysterious past and Chief Boden’s grand plans take a detour.
All seems lost with firehouse 51 on the verge of closing its’ doors, thanks in no small part to Gail McLeod, but Chief Boden and the rest of the house refuse to allow themselves to sit by and let it happen. An emergency call to an apartment structure fire tests everyone’s limits and puts the squad in harm’s way. Meanwhile, Dawson receives some life-changing news and union president Greg Sullivan makes headlines, which has an immediate impact on Mouch.