Ragnar goes on a trip of initiation with his son. Meanwhile, he thinks he has finally found a way to sail ships to the west. However, his beliefs are seen as insane so he chooses to go against the law.

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.

After his successful raid, Ragnar and his crew joyously return home with their riches. Earl Haraldson doesn't hesitate to summon Ragnar to the great hall where he lays claim to the entirety of the treasure. He allows the crew to take one thing from the hoard and Ragnar selects Brother Athelstan as his slave. From Athelstan, he learns the political structure in England and wants to learn some of the language. Haraldson sanctions a new raid but insists that one of his men, Knute, join Ragnar's crew. Ragnar takes his wife this time and surprises everyone by putting Athelstan in charge of the farm.

The Vikings head back to England to see what other treasures this new world has to offer. This go round Ragnar and his crew sail out with Earl Haraldson's permission.

In the Great Hall of Kattegat, a seer reads Earl Haraldson's future and tells him that Ragnar Lothbrok searches for his death.

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.

Three Viking ships sail upriver towards the very heart of power in eastern England: the Royal Villa of King Aelle.

The traditional pilgrimage to Uppsala to thank the gods brings a torrent of emotions for Ragnar, Lagertha, and Athelstan.

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.

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.

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; 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 becomes confidant to King Ecbert.

Ragnar and King Horik clash over differences; King Aelle arrives in Wessex; Ecbert has an eye on a new alliance.

Princess Aslaug's latest prophecy comes to fruition; 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 vicious surprise.

Ragnar returns to Kattegat after the defeat in Wessex and places his trust in those who have stayed by his side all this time.

Ragnar and Lagertha's fleets depart Kattegat once more for Wessex but this time they bring settlers.

Lagertha and Athelstan help to set up the Viking settlement; a mysterious wanderer turns up.

King Ecbert visits the developing Viking settlement as the first harvest is sown.

There is bitterness in the camp, Floki is angry over the alliance with Ecbert.

The fleet returns to Kattegat to discover tragic circumstances await.

Preparations for the Paris raid pick up speed, and Rollo thinks about the Seer's prophecy.

The Viking fleet causes panic in Paris; the Emperor Charles declares he will remain in the city.

The Viking army sets out and Paris goes into lockdown as the army prepares the defense.

The Vikings hit Paris with a second assault; Emperor Charles has to make a difficult decision.

With one last chance to take Paris, Ragnar and his Viking troops take a daring chance. Ragnar asks Bjorn for a favor that could change the course of Viking history.

As Ragnar lies in his sick bed in Kattegat, events unfold beyond his control.

Ragnar tells Floki he has to pay a heavy price for his actions. Rollo finds an ally in Count Odo. Bjorn Ironside finds more than he bargained for in the wilderness.

Ragnar gets to know the new slave woman while Rollo reveals his ambitions to his wife. Bjorn meets an unexpected warrior on his way home.

Halfdan the Black arrives in Kattegat. Floki reveals a secret to Finehair. Ragnar and Yidu become closer. Meanwhile Lagertha settles a score.

Ragnar reveals his plan to raid Paris again, and although the fleet is storm-tossed as it sets out, the challenge lies in Frankia where Rollo awaits. Meanwhile, Ecbert dispatches Aethelwulf and Alfred on a pilgrimage to Rome.

Now aware that Rollo has betrayed him, Ragnar carries out his plan of attack, which has dire consequences. Ecbert is given an offer from Prince Wigstan of Mercia. Harbard causes a stir with the women of Kattegat.

After facing defeat on the river, Ragnar refuses to retreat, prompting him to change his methods of attacking Paris. Count Odo's plot against Charles and Rollo backfires. Ecbert now rules Mercia, which dissatisfies Kwenthrith.

The Vikings finally reach the river. Aethelwulf and Alfred reach Rome. Erlendur makes his move against Bjorn. Sigurd makes a shocking discovery in Kattegat. Ecbert is crowned king in Mercia.

A ferocious battle between the Vikings and the Franks eventually comes down to Ragnar against Rollo. The outcome will seal the fate of the two brothers.

Ragnar has returned to Kattegat where he devises a plan to return to Wessex to right past wrongs.

Ragnar seeks to equip his voyage to Wessex, even while being warned that the gods have deserted him. Bjorn prepares to fulfill his dream of exploring the Mediterranean.

Ragnar and Ivar face a difficult decision in regards to their crew; Bjorn has an unexpected reunion.

Lagertha attempts to fulfill a long-held ambition; Ragnar negotiates an unexpected concession from King Ecbert.

King Aelle can't hide his pleasure when Ragnar arrives in a cage and shows him no mercy.

Bjorn's fleet sails onward and launches a surprise attack. Back in Kattegat, Lagertha continues in her quest for power.

The Great Army is gathering in Kattegat, as Lagertha is saved by Bjorn Ironside from the hands of Ragnar's sons. Rollo is establishing the kingdom of Normandie as a safe-heaven for all vikings in search for land.

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 Kingdom of Wessex.

Guided by Bishop Heahmund's visions, the Saxons devise a battle plan. Ivar the Boneless strategizes on his own as the Vikings undergo increasing pressure. Bjorn Ironside finds himself in a new territory and must convince the local commander he is a trader and not a raider.

As the Vikings establish their stronghold in York, Ivar is determined to lead the Great Army. In Kattegat, Lagertha misjudges King Harald and pays a heavy price. Floki arrives at a mysterious land.

Guided by Bishop Heahmund's visions, the Saxons devise a battle plan. Ivar the Boneless strategizes on his own as the Vikings undergo increasing pressure. Bjorn Ironside finds himself in a new territory and must convince the local commander he is a trader and not a raider.

Ivar meets his match in Bishop Heahmund. Floki returns to Kattegat. Bjorn receives a lavish welcome in North Africa.

Lagertha is betrayed, and Bjorn must find a way to support the distraught queen; Floki and his settlers arrive in a new land, but it is far from what they expected.

Bjorn returns to Kattegat to learn that an attack will take place during the next full moon; Ivar must decide if he can place his trust in a former enemy on the battlefield.

The battle for Kattegat begins. As the two armies line up to fight, the Great Heathen Army must decide between a final plea for peace or all-out war. Floki faces discord amongst the settlers.

The army leaders consider their options in the aftermath of the battle. In Floki's camp, all hopes of binding the community together are dashed as tragedy unfolds.

A sense of doom looms over Kattegat as bloodshed ensues, but as the defeated army flees in the face of the victors, a legendary warrior makes his way home.

Ivar is crowned the new king of Kattegat just in time to welcome Rollo home; Bjorn, Lagertha and Ubbe must rely on unsteady alliances to survive.

Bjorn, Lagertha and Ubbe face an uncertain fate as Heahmund's loyalty is tested; Floki fights to understand the will of the gods in Iceland; Ivar may have met his match in Kattegat.

Heahmund must convince King Alfred that his actions are in defense of the crown; Ubbe and Torvi strengthen the position of the Vikings, but not all in the Viking camp support their strategy; another settler disappears in Iceland.

King Harald and his army approaches Wessex while Aethelred is about to make a huge decision about his brother's fate.

Bishop Heahmund is wracked with guilt as he fights to renounce his passions. Viking will clash with Saxon on the battlefield leaving a key figure lost in the balance.

Ubbe achieves one of Ragnar's dreams; Ivar hatches a new plan in Kattegat, while preparing for a divine arrival; a settler in Iceland returns in a terrible state; King Alfred faces his greatest threat yet.

Hvitserk is severely tested. Floki makes an amazing discovery. Freydis gives Ivar a surprise. Ubbe negotiates with the three Danish Kings that have massed their armies in Reading, but the negotiations may have a perilous outcome.

Ubbe is forced into hand-to-hand combat. Floki reaches new depths and is met by a shocking sight. Bjorn sets off for Scandinavia with an old rival.

A new battle for Kattegat is on and only the gods know who will emerge victorious.

Bjorn struggles with the responsibilities of kingship and finds he can't rely on his mother, Lagertha; she has other plans. Ivar falls into the hands of Kievan Rus, and in their ruthless and unpredictable ruler, Prince Oleg, he may finally have met his match.

Messengers arrive in Kattegat with news that presents Bjorn with a dilemma. As Bjorn attempts to do the right thing as ruler of Kattegat, Prince Oleg of Kiev seems untroubled by his conscience.

Lagertha is forced to take action; In Kiev, although Oleg continues to be friendly, Ivar is aware of the threat which Oleg poses to the vulnerable young heir to the throne; Bjorn has answered the call and come to the aid of an old enemy.

Lagertha leads her village's response to the recent attacks but despite her best efforts, when the inevitable attack comes, the consequences are tragic. Olaf has a bold new plan for the future of Norway. In Kiev, although Ivar discusses Oleg's ambitions for Scandinavia, he's actually more interested in the plight of Igor, the young heir who Oleg controls.

Norway's Kings and Jarls arrive at Harald's territory for the election of the King of all Norway, while King Olaf is confident of the result, the election may not run as smoothly as he thinks.

Bjorn is forced to act quickly in the aftermath of the election for the King of all Norway. The bandits attack Lagertha's village again, confident of victory. But when the defense boils down to single combat with Lagertha, victory for the bandits looks less certain. Back in Kattegat, haunted and paranoid, Hvitserk continues to unravel.

Bjorn returns to Kattegat; Harald gains a measure of revenge on Olaf; in Kiev, interesting news reaches Ivar and Igor about Prince Dir.

Bjorn is forced to act quickly in the aftermath of the election for the King of all Norway. The bandits attack Lagertha's village again, confident of victory. But when the defense boils down to single combat with Lagertha, victory for the bandits looks less certain. Back in Kattegat, haunted and paranoid, Hvitserk continues to unravel.

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.

Lagertha leads her village's response to the recent attacks but despite her best efforts, when the inevitable attack comes, the consequences are tragic. Olaf has a bold new plan for the future of Norway. In Kiev, although Ivar discusses Oleg's ambitions for Scandinavia, he's actually more interested in the plight of Igor, the young heir who Oleg controls.

Lagertha and Ragnar unite once again; Aslaug must face the truth of her prophecies; Athelstan struggles to define his faith; Bjorn must once again make a choice.

Bjorn returns to Kattegat; Harald gains a measure of revenge on Olaf; in Kiev, interesting news reaches Ivar and Igor about Prince Dir.

Halfdan the Black arrives in Kattegat. Floki reveals a secret to Finehair. Ragnar and Yidu become closer. Meanwhile Lagertha settles a score.

King Horik returns to Kattegat with a surprising proposition for Ragnar; Lagertha runs into a less than enthusiastic homecoming from her new husband; Athelstan becomes confidant to King Ecbert.

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.

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.

Princess Aslaug's latest prophecy comes to fruition; Ragnar and Horik have very different ideas about the true purpose of their trip to Wessex.