Vikings follows the adventures of Ragnar Lothbrok the greatest hero of his age. The series tells the sagas of Ragnar's band of Viking brothers and his family, as he rises to become King of the Viking tribes. As well as being a fearless warrior, Ragnar embodies the Norse traditions of devotion to the gods, legend has it that he was a direct descendant of Odin, the god of war and warriors.
Ragnar and Lagertha's fleets depart Kattegat once more for Wessex but this time they bring settlers. King Ecbert hosts the Vikings and proposes a deal. Despite the misgivings of some of the other leaders, Ragnar leads his forces into battle once more, but this time as allies of Wessex.
Lagertha and Athelstan help to establish the Viking settlement in Wessex. Harbard, a mysterious wanderer, arrives in Kattegat, realizing the forewarned dreams of Aslaug, Siggy and Helga.
King Ecbert visits the developing Viking settlement as the first harvest is sown and rebuffs criticism from his leading nobles. In Mercia, the Wessex/Viking forces charge at the battle at the Hill of the Ash. In Kattegat, Harbard arrives in to the Great Hall and his mysterious aura fascinates Aslaug and Helga but Siggy remains suspicious. There are strange and tragic happenings in Kattegat, and Siggy suspects Harbard is the cause.
The victorious Wessex/Viking forces return to Wessex but there is rancour in the Viking camp–Floki is angry over the alliance with Ecbert and resentful the influence that he feels Athelstan has over Ragnar. Princess Kwenthrith makes some calculating political moves following the battle at the Hill of the Ash in Mercia. Visitors from the past arrive in Hederby, at Kalf’s invitation.
The fleet returns to Kattegat to find tragic circumstances await. Lagertha learns that her Earldom has been usurped and convinces Ragnar to travel to Hederby with her in an effort to reclaim her title. Ragnar causes great surprise when he announces the next raid. The Seer has interesting prophecies for Rollo.
Preparations for the Paris raid pick up pace. Porunn and Judith both deliver children, and with new life there is also death. Athelstan tells Ragnar of his re-connection to his Christian faith. Floki interprets a sign from the gods that a sacrifice should be made.
The appearance of the Viking fleet causes panic among the population of Paris. The Emperor Charles, urged by his daughter Gisla, announces in Court he will remain in the city. The defense of Paris is in the hands of its Commander, Count Odo, who hopes that a heroic victory against the Vikings will gain him Gisla’s hand in marriage. The Vikings establish camp downriver from the city and plan their attack.
The Viking army embarks and Paris goes into lockdown as the army prepares the defense, overseen by Odo. The Vikings are determined to make it through the gates of Paris and will stop at nothing to succeed.
The Vikings go all out for a second assault on Paris. Recognizing the desperate state of affairs for his city, Emperor Charles must make a difficult decision. In Wessex, Judith is compelled to make a difficult decision of her own.
The battle begins between Ragnar and King Horik's forces against Jarl Borg. Borg is joined by Rollo, and this Viking clash pits brother against brother. There can only be one victor. Meanwhile, Princess Aslaug makes her way to Kattegat and brings with her a surprise that leaves Ragnar in a difficult predicament.
Four peaceful years have since passed with Ragnar as Earl. The time has come for an unlikely alliance to band together in pursuit of a common goal: a new raid on England. A storm pushes the Viking fleet to a new destination, and on the beaches of Wessex, Ragnar and his men may have met their match.
The Wessex Viking raid is in full swing and King Ecbert finds himself facing an entirely new kind of foe. While Ragnar races to dominate in the West, Jarl Borg has his own plans in store for the future of Kattegat.
A meeting between two great men may pave the way for future compromise as Ragnar and Ecbert come face to face. Jarl Borg now rules Kattegat and with an iron fist and Rollo must now become the leader his people need in Ragnar's absence.
Lagertha and Ragnar unite once again and together fight to win Kattegat back from Jarl Borg. Aslaug must face the truth of her prophecies. Athelstan struggles to define his faith. Bjorn must once again make a choice.
King Horik returns to Kattegat with a surprising proposition for Ragnar. Lagertha runs into a less than enthusiastic homecoming from her new husband. Athelstan, struggling with his own inner demons, becomes confidant to King Ecbert.
Ragnar and King Horik clash over how to dispense justice to Jarl Borg. In Wessex, King Aelle arrives and Ecbert has an eye on a new alliance.
Princess Aslaug's latest prophecy comes to fruition as she readies to give birth once more; Ragnar and Horik have very different ideas about the true purpose of their trip to Wessex.
Ragnar's warriors march on to King Ecbert's villa and are met with a surprisingly vicious welcome party.
Ragnar and King Horik return to Kattegat; Ragnar places his trust in those who have stood by him.
In 8th century Scandinavia, Ragnar Lothbrok is a warrior and a farmer who dreams of finding riches by bucking the tradition of raiding to the east. Ragnar has been working in secret on a project that will turn the Viking world on its head. But first Ragnar must convince the leader of his community, the powerful Earl Haraldson, who is none too happy to share in the renown that this journey could bring to Ragnar if it's successful.
The stage is set for the first journey west by Ragnar Lothbrok as he gathers a crew willing to risk their lives to travel into the unknown. Earl Haraldson's paranoia reaches new heights as it becomes apparent that trust is hard to come by in this dark era.
A monastery in Lindesfarne is about to get a firsthand look at how the Vikings operate. In and out in a flurry of violence and terror, Ragnar and his crew raid the monastery for everything it contains, from treasure to monks who can be sold as slaves. Unable to ignore the riches this unsanctioned journey has returned, Earl Haraldson has no choice but to agree to let these warriors undertake a second trip out. The West has now been opened for the taking by Ragnar Lothbrok, and the world of the Vikings will never be the same.
The Vikings head back to England to see what other treasures this new world has to offer. Ragnar and his crew sail out with Earl Haraldson's permission… and also with Earl Haraldson's spy. After bloodshed on the beach, the Vikings choose the Sabbath to invade the town of Hexam and unleash a flood of violence and panic. In the midst of the terror, Ragnar and Lagertha discover that there are consequences for every action and Earl Haraldson is always watching.
In the Great Hall of Kattegat, a seer reads Earl Haraldson’s future and tells him that Ragnar Lothbrok searches for his death. The unanswerable question is whom do the gods favor more? As a man willing to defend his power and status to the death, Haraldson intends to take precautionary measures. Ragnar, his home and farm burned by the Earl is hurt but hidden safely away. He must now choose the path that will lead him back to his freedom.
Ragnar, weak and still hurt, must meet the Earl head-on after it comes to light that Rollo has been tortured on Haraldson’s orders. The two men will come together face to face with a single outcome possible: Only one man will leave this fight alive.
Three Viking ships sail upriver towards the very heart of power in eastern England: the Royal Villa of King Aelle. Ragnar Lothbrok has come looking for ransom in exchange for peace. However, King Aelle has a different plan in mind for these northern heathens.
The traditional pilgrimage to Uppsala to thank the gods brings a torrent of emotions for Ragnar, Lagertha, and Athelstan. Ragnar, pulling farther away from his wife goes to make peace with the death of his unborn son. Lagertha, still reeling from her miscarriage, wants to find out from the gods if more sons are in her future. As the Vikings come together to sacrifice and give thanks to their gods, Athelstan discovers just how strong his Christian faith still is.
At the behest of King Horik, Ragnar assembles a small party to travel to Gotaland (modern day Sweden) to resolve a land dispute with the area’s leader, Jarl Borg. Ragnar’s renown precedes him and Jarl Borg is intrigued – has he found a new ally or is Ragnar just a puppet of the king? Meanwhile in Kattegat, with a plague taking its toll on the village, the people look to Lagertha to help appease the gods.
Entry to Valhalla eludes Ragnar, but as he lies in his sick bed in Kattegat events unfold beyond his control. Bjorn orders the arrest of Floki for Athelstan's murder while in Paris, Rollo betrays the last of his Viking supporters to strengthen his position in the French court. In Hedeby, Kalf announces joint earldom with Lagertha, but is power sharing Kalf's true intention and is Lagertha actually willing to share what once was hers?
As Ragnar and Floki remain at odds, Rollo makes great efforts in Paris to win over his new bride, Princess Gisla. Meanwhile, King Ecbert sets the task for his son Aethelwulf to rescue Queen Kwenthrith.
Ragnar informs Floki of a heavy price he has paid for his actions; Rollo finds an unlikely ally in Count Odo; Bjorn has to fight a fierce opponent in the wilderness.
King Aelle goes to Wessex for Christmas and is not impressed with how family relations are developing; Rollo's future hangs in the balance.
There's an air of betrayal as those whom Odo trusts plot against him; Ecbert agrees to support Kwenthrith in Mercia; Pregnancy brings happiness to Lagertha and Kalf and a marriage is arranged.
Ragnar declares another raid on Paris at the Thing in Kattegat; Ecbert also has a journey in mind as he dispatches Aethelwulf and Alfred on a pilgrimage to Rome.
In England, King Ecbert's true ambitions are revealed as he plans to gain the crown of Mercia. While outside Paris, the Vikings attack with considerable force, but can they overcome Rollo's defenses? Meanwhile, Harbard, the mysterious wanderer, returns and causes a stir amongst the women of Kattegat.
Defeat for the Vikings calls Ragnar's leadership into question as they evacuate their camp and move back down river. Ragnar remains inscrutable until he orders the fleet to beach at a cliff face and unveils an ingenious plan. Rollo and Gisla have news that strengthens Rollo's position at the French Court whilst Count Odo fails to identify his true enemies, with fatal consequences.
The labors of the Vikings eventually bear fruit as, within sight of Paris, they re-launch their boats but this time along with some interesting structures that Floki has built. Aethelwulf and Alfred eventually arrive in Rome and honors are conferred by Pope Leo but relations are not so cordial in Wessex between King Ecbert and the disgruntled King Aelle.
A ferocious battle between the Vikings and the French eventually comes down to Ragnar against Rollo. The outcome will seal the fate of the two brothers.
Ragnar's reappearance in Kattegat triggers a chain of events no one - except the Seer - could have ever imagined. He unexpectedly arrives home to see what has become of his sons and to handle unfinished business in Wessex with King Ecbert. Meanwhile, Lagertha plans a power play in Kattegat and Bjorn prepares to fulfill his long-held dream to explore the Mediterranean in a sleek new boat built for him by Floki.
The Kattegat locals chide Ragnar that the gods have deserted him as he struggles to crew his voyage to Wessex. It's Bjorn who has charisma now as he prepares to fulfill his long-held dream to explore the Mediterranean in a sleek new boat built for him by Floki. By contrast, Ragnar must accept weathered boats and a crew he has bribed but when Aslaug foresees that the fleet will be lost in a vicious storm her warnings go un-heeded by Ragnar and her precious son, Ivar.
Ragnar's fleet is shipwrecked and washes up on the Wessex coast, but without enough survivors to form a credible force, Ragnar and Ivar have a difficult decision to make. Rollo meets his Viking comrades again and can't resist the urge to join Bjorn's voyage, risking his marriage and his new Frankish identity. Ragnar too is taking a risk as he carries Ivar towards the Royal Villa in Wessex – throwing himself and his son upon the mercy of King Ecbert.
Lagertha attempts to fulfill a long-held ambition; Ragnar negotiates an unexpected concession from King Ecbert.
Ragnar and Ivar plot against the Saxons and reach a new level of understanding.
Bjorn's fleet sails onward and launches a surprise attack; back in Kattegat, Lagertha continues in her quest for power.
The Viking army begins to gather in Kattegat; Lagertha must remain vigilant in the absence of her son, Bjorn.
Ragnar's plan comes to fruition; the Viking army lands on the coast of Northumbria.
The Viking army causes panic in the English countryside as King Ecbert and Aethelwulf plan the defense of the realm.