It’s six months after the battle of Kattegat and Bjorn is now King. As he struggles with the responsibilities of kingship, he finds he can’t rely on his mother. Ivar falls into the hands of the 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. Prince Oleg of Kiev seems untroubled by his conscience. Lagertha has settled into her new, peaceful life, but danger lurks nearby.

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.

In Iceland, Ubbe and Torvi finally meet a mysterious wanderer. Bjorn is forced to re-think who his enemies are when Erik returns from a scouting mission with worrying information. Bjorn will need allies, but he may not be able to convince his old foe, King Harald, to join forces in the face of the new threat. Ivar is reunited with someone close to him.

Ivar and Igor may be plotting against Oleg, but they're still part of the force that departs Kiev to invade Scandinavia. King Harald and King Bjorn begin furious preparations for the invasion.

In Iceland, Ubbe learns the truth about Kjetill and has a difficult decision to make. Back in Norway, the battle against the Rus has had grave consequences. But re-enforcements have arrived, and Bjorn has an idea that may yet save the day.