Without a Trace is a fast-paced procedural drama about the Missing Persons Squad of the Federal Bureau of Investigation. The sole responsibility of the special task force is to find missing persons by applying advanced psychological profiling techniques to peel back the layers of the victims' lives and trace their whereabouts in an effort to discover whether they have been abducted, been murdered, committed suicide or simply run away. The team reconstructs a "Day of Disappearance" timeline that details every minute of the 24 hours prior to the disappearance, following one simple rule: learn who the victim is in order to learn where the victim is. Senior agent Jack Malone (Anthony LaPaglia) heads the dedicated team that knows too well that every second counts when someone vanishes.
Bryan Parker is questioned by the FBI after being found alone on the road by a police officer, his hand bandaged. He tells them about a young boy his father had abducted, and soon the team is searching for Todd. The search initially goes nowhere, and Sam continues to question Bryan, but they get a lead when Bryan identifies a snapshot of the boy that reveals his identity to be that of missing boy Daniel Ellison. It isn't long before the squad realises that Daniel isn't the first boy that Parker grabbed, and follow his past to find him and the missing boy.
Cindy Peterson, a mother who had become a stripper to support her family, goes missing after work one night, and Jack sends Elena in undercover at the strip club to learn what she can. Danny moves in to keep an eye on her after someone catches on to her spying, while Vivian discovers that Jim Peterson hasn't been completely honest with them. Jack faces censure from Olczyk over his relationship with Ann, and is angry with Ann after she admits to him that she thinks he let their relationship cloud his judgment in the Davis investigation.
The team searches for Jessica, a 911 operator who disappeared after a man called and asked for her by name.
The team investigates when Malia Norton, a teenager at a detention center, disappears after being threatened by one of the other residents. Malia had been involved in a drinking and driving accident that had seriously injured her sister's boyfriend and killed another young man. The investigation at the detention center uncovers a lot of secrets that some of the residents would prefer to keep well hidden.
Jack and the team investigate when Sadik Marku's son goes missing along with the boy's mother, and Samantha worries that Jack is more interested in settling an old score with Marku than with finding the missing woman and boy.
The team investigates when Aaron Gibbs ends up missing one night and soon learn that he had been lying to his wife about quitting his job, and had been working nights in a fight club. During the course of the investigation, Jack and the others learn that Aaron's disappearance was connected to events that took place during Hurricane Katrina, when Aaron was fighting to save his sons, and follow the trail of evidence, believing that the events of that night in New Orleans hold the key to finding the truth about the missing man.
Jack and the team investigate the disappearance of Alex Stark after his girlfriend reports him missing, and soon learn that Alex didn't own a cleaning business like he said he did but was actually involved in an illegal gambling operation. Jack goes undercover at a club that Alex would gamble at to find out what happened to him, and ends up being taken hostage by an associate of Alex's who becomes convinced that Jack is actually there to kill her. Unfortunately for Jack, his team believes that he has changed his cover story and has no idea that he's actually been kidnapped.
The team investigates the disappearance of social worker Eric Hayes, who had given thirty days notice to his job not long before. When their investigation leads them to a young pregnant woman who had already lost one child to the system, the agents begin to believe the disillusioned social worker may have been having an affair but soon discover that he may have been trying to right the wrong that drove him from his job. Danny has trouble with the investigation, as it reminds him of his own experience in foster care. Jack confides in Samantha about his relationship with Ann, but it may be too late.
Vivian thinks about her recent surgical problems while searching for a missing woman with a terminal condition.
When 17-year-old Ted Soros goes missing after a basketball game, the team begins an investigation, soon learning that Ted was an emancipated minor who was living on his own to attend a school with an exemplary basketball program. Learning he had recently contacted his mother with a request for legal advice from an uncle, the team begins to suspect that Ted may have done something that he could face criminal charges for, and realise that Ted's secret is connected to a university recruiting party. While the team works Ted's disappearance, Jack learns from Ann that she lost the baby, and waits for her at the clinic while she seeks medical attention.
The team tries to determine whether or not the recent disappearance of an air traffic controller has connections to the Middle East. The team soon learns that his wife died in an automobile accident and he was having an affair with her sister.
When a young artist disappears, the team is concerned that one of her subjects may have been unhappy with her work.
The team searches for missing water plant supervisor Jason Turner, and learn that he had become the target of a lot of anger after recent layoffs at the plant. Carlos comes to the office looking for Elena.
Elena is frantic when her daughter Sofie goes missing, and the team has a full schedule as they must also search for a missing female tourist named Jenny.
A newly elected senator goes missing and Jack immediately turns his attention towards her husband.
The team searches for a fifteen-year-old girl who lived with her grandfather and was last seen at an Internet café. Sam gets an unexpected visit from her estranged sister.
Sam's darkest secrets are revealed when her sister goes missing she decides to search for her without the team's help.
When a young, interracial boy goes missing, race and money appear to play the starring roles in the investigation.
A former soldier, now stuntman, goes missing and the team learns that he changed his will only short time before he went missing which makes them wonder who needed the money.
The team searches for Chris Manning, a family court judge with a soft side who went missing after meeting with a young boy caught between his mother and his abusive father. Suspicion initially turns anyone Manning may have riled up due to his court rulings, but after his clerk is shot in what appears to be an attempt on Manning's life, the team learns that the secret behind Manning's disappearance is tied up with something that happened over twenty years earlier.
A high school student goes missing after leaving her prom early to get some rest in her hotel room, leaving behind a bloody dress and a lot of questions about what may have happened to her.
A teenage girl disappears after joining a cult. In the office, Elena encounters problems with Carlos in their custody battle for Sofie.
A man, whose daughter went missing years ago, also goes missing, and the team tries to connect his desire to help another couple missing their son. Meanwhile, Jack is trying to adjust to his new boss, Clark Medina.
A rising exec is abducted from a Taxi after attending a rooftop party. The team also continues to learn to adjust with their new boss.
A white-collar criminal goes missing on his way to testify against a former associate and the team must find out why.
The team discovers a long festering secret which sets off a deadly chain of events when they investigate the disappearance of the teenage son of a Secret Service man.
The team must shift their attention from a case they are working on and hand it over to Martin, after a child is reported to have been kidnapped at a mall.
The team finds a secret to a bank manager's past after she vanishes, which may just hold a clue to her disappearance. Meanwhile, Jack is named head of the department once again.
The team searches for a paraplegic who had been injured two years earlier in a car accident and is now missing. Their investigation shocks them when they discover the truth in what may have caused his disappearance.
Jack and Samantha head to Los Angeles to look into the disappearance of a man who vanished after attending a funeral.
The team must decide whether or not a doctor's past is a factor in her disappearance.
A TV weatherman arrives at work bleeding from his side and the team tries to beat the clock to find out what that has to do with disappearance.
The team is called in to investigate the custody kidnapping over a teen who vanished after last seen with her mother. But the case takes a turn when they discover the teen was living a secret life. Meanwhile, there is a bump in the road of the relationship between Jack and Samantha.
The team searches for a bar owner who goes missing shortly after his statue of St. Theresa cries. Brian's visit takes a new turn.
Elena is forced to face the consequences of her past, as the team is put on the case to search for her former partner who went missing during an undercover sting.
The team tries to hunt down the person who kidnapped two neighbors from a suburban home. The case takes a surprising turn when the agents discover the identity of the abductor.
The team uncovers a history of deception as they search for a man posing as a college student vanishes.
The team investigates after a woman attends a self-defense class with her infant son and then both disappear after the class ends.
While working on a high profile civil case, a trial consultant vanishes. Jack and Sam learn how to make adjustments as Brian and Finn spend more time together.
The team believes that the past of a missing psychologist's brother might have played a role in his disappearance. Martin's relationship with Kim takes a spicy turn.
The suspect list keeps growing as the team investigates the disappearance of a Russian matchmaker.
A billionaire's son disappears after crash landing a small plane in the woods. Kim Marcus returns and her relationship with Martin develops.
The team looks for a missing journalist after her hardcore exposes are published on an on-line magazine. They begin to suspect a politician, the subject of one of her latest entries. Meanwhile, Brian remains in Sam and Finn's life.
The team searches for a missing teen who's abductor left behind an amateur tape with her appearing on it.
After Hannah's boyfriend disappears from Chicago along the way to New York, Jack hesitates to assign the team on his case.
The team searches for a man who goes missing after a late night dive and try to zero in on who could be responsible for his disappearance. Meanwhile, Danny and Elena take their relationship to another level.
The four-year-old adopted son of a celebrity couple is kidnapped, and the team must determine if the reason has to deal with the parents' status or the boy's own Sudanese origin.
The team considers if a father who cleans crime scenes for a living led to his disappearance with his daughter.
The team searches for a missing mother who they believe may be searching for her son, who is also missing.
When a woman disappears after her boyfriend is killed by the police, the team suspects gang involvement. Later, Sam learns she's pregnant.
An office shooting forces a woman to disappear, possibly to hide a deep secret.
(Crossover episode with CSI: Crime Scene Investigation, Season 8 Episode 6.) Malone's team joins forces with Gil Grissom, a CSI from Las Vegas, and his team as they track a serial killer with ties to New York.
When a college student disappears after making racial remarks in a class, the team wonders if those may be directly connected to his disappearance.
The disappearance of an ultimate fighter leads the team to investigate his background, where they learn the man had a number of enemies.
The team determines if an ex-con's past criminal activity caused her to disappear after visiting a prison inmate. Det. Mars and Agent Johnson also continue their investigation.
A child prodigy turned store Santa vanishes and the team wonders if he had criminal connections.
Malone and his team start off the new year investigating how a private investigator might have went missing.
The team work on a case where a veterans-hospital worker vanishes and have two leads.
Jack goes missing after taking a case into his own hands which soon becomes intertwined with a human trafficking prostitution case that Vivian is working on.
While struggling to deal with the aftermath of Jack's accident, the team searches to find a teen heart transplant recipient, believing her disappearance might be connected to her donor. Samantha talks to Brian.
The team searches for a coma patient who had woken up after three years only to disappear.
After the latest lottery winner goes missing, the team works to figure out why.
A truck driver goes missing after saving a boy's life, and the team determines if that has anything to do with his disappearance. Meanwhile, Jack's mental health is examined by a psychiatrist.
Five people with an odd connection go missing from a coffee shop, and the team determines what the connection had to do with their disappearance. Meanwhile, Spade gets ready for the birth of her child.