Thorfinn, a boy living in Iceland, longs for adventure and is eager to know more about the world. He dreams of a land of paradise called Vinland that he hears about from the adventurer Leif, while he leads his peaceful life with this father Thors, a former warrior. One day, Thors saves a runaway slave and sets a series of events in motion. This is the story of a true warrior in an age of turmoil.

Askeladd, the leader of a Viking army of a hundred men, receives orders from Floki of the Jomsvikings to kill Thors, who was once known as the Troll of Jom. However, the villagers, completely unaware of the order, buzz with excitement as they prepare for their first battle. Thorfinn also joins in the excitement. Thors and his men are about to embark on a difficult sea journey to England.

Thors and his men fall for Askeladd's trap and faces a dangerous situation, but Thors defeats many of Askeladd's men with his overpowering strength. However, Thors knows that it will be difficult to save everyone, including his son, who've been living in a peaceful village their entire lives, and makes a tough decision.

After Askeladd kills Thorfinn's father Thors, Thorfinn hides inside Thor's ship and bides his time until the opportunity to take revenge. However, life on the ship is harsh without any food or water, and Thorfinn grows weaker day by day. One day, Thorfinn, armed with his sword, attempt to attack Askeladd in his sleep...

Thorfinn kills his first man. As more time goes on Thorfinn kills more men and becomes more skilled. One day when Thorfinn is in battle he gets shot with an arrow and ends up unconscious. An English woman and her daughter help him recover.

Askeladd withdraws temporarily from the war against England. While searching for a new source of income, he encounters a skirmish among the Franks and hatches a plot to steal their treasure. Askeladd sends 16 years old Thorfinn, who has grown up into a cold-hearted Viking, ahead as a messenger.

In October 1013, King Sweyn leads a fleet of Danish and Viking ships in an attempt to take London Bridge of England. Askeladd's army, hired by the army of Denmark, was among them. However, after the betrayal of Thorkell the Tall, a Viking known for his overpowering strength, London Bridge has become impregnable. Askeladd tells Thorfinn he'll reward him with a duel if he's able to kill Thorkell.

Canute’s party arrives in York to attend the Imperial Council. Although Canute had wanted to strike out against King Sweyn, the King was being guarded by the most powerful Jomsviking unit in the Northern Sea while keeping a close eye on Canute. With the situation strained to the breaking point, Askeladd comes up with a plan. Meanwhile, Thorfinn is reunited with a person who knew his former self.

Thorfinn begins his duel against Askeladd with Canute and Thorkell as witnesses. However, Thorfinn is unable to strike as he stands overwhelmed by the extraordinary mood that overtakes Askeladd after Bjorn's departure. Having noticed Thorfinn's hesitation, Askeladd lays down his sword and provokes Thorfinn into an unarmed fight, which incites Thorfinn's fury.

Einar lives peacefully in northern England with his mother and sister, but then one day, their village comes under attack.

Einar and Thorfinn are told to convert a wild forest into a wheat field; and if they succeed, they will have the chance to buy their own freedom.

Thieves have been stealing food from Ketil's farm. Meanwhile, Ketil's eldest son Thorgil returns home.

Thorfinn has nightmares almost every night, but he can never remember what he dreamed about — and that bothers him.

Olmar feels insulted by Canute's messenger and, encouraged by his older brother Thorgil, takes matters into his own hands.

Einar says that even if he gains his freedom, he wants to stay near Arnheid. Snake hears news of a slave who killed his owners, and is now on the run.

A runaway slave appears on Ketil's farm, claiming to be Arnheid's husband. But before he can free her, he's confronted by Snake.

Arnheid comes to the fortress where Gardar is imprisoned. She wants to see her husband and treat his injuries.

Snake strikes quickly, surprising Thorfinn with his speed and agility. As he lies wounded, Gardar thinks back on the life he shared with Arnheid.

After returning home to his farm, an exhausted Ketil starts searching for Arnheid, only to find out what happened in his absence.

Amidst the confusion of a peasant uprising, Thorfinn and the others try to escape, carrying a severely injured and pregnant Arnheid.

As Thorfinn and Einar head for their escape, Arnheid regains consciousness and asks where they are going — and if there are slaves and wars there, too.

The battle has left heartbreaking casualties in its wake. Though Thorgil and Ketil's wife want to continue the fight, Canute demands their surrender.

At long last, Thorfinn returns to Iceland and finds a moment of happiness, reunited with his loved ones. But soon, he opens up about his next journey.