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.

In the year 1002, the war between England and Denmark was intensifying. One day, the Jomsvikings pay a visit to Thorfinn's village in order to bring back Thors, their former commander, to prepare for the impending battle. Thors is forced to join the war in order to protect the villagers from being taken hostage, and must face his accursed past in order to save his family and his village.

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 capturing the treasure from the Franks, Askeladd's men return to the village of Gorm on the Jutland Peninsula in Denmark to pass the winter. Thorfinn challenges Askeladd to a duel as a reward for bringing him the head of the captain of the clan of Franks. Even though Thorfinn has grown in skill through his experience in battle, he is still no match for Askeladd.

Askeladd's army separates from the army of Denmark and attacks a village 100 km to the west. Thorfinn leaves the soldiers behind in disgust and climbs up a hill overlooking the village, where he pledges revenge for his father. However, he encounters Askeladd sitting in the darkness, who tells him about "Britannia", the aging of the world, and Ragnarok, the final battle.

Thorfinn suffers a serious injury in his fight against Thorkell. Thorfinn is told to think about what he has to do to beat Thorkell. Askeladd treats Thorfinn’s wounds so that he may fight again someday, and proposes a joint strategy to help the two of them survive longer.

Thorfinn wakes up in a peaceful place and he sees his father again. But then things quickly turn dark, and Thorfinn must face his painful past.

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.