Plotting to avenge a massacre in England, Viking armies converge in Kattegat — but siblings Leif and Freydis exact a different kind of retribution.

To save the life of Freydis, Leif agrees to join Canute and Harald's siege of London. Queen Emma dispatches stepson Edmund to secure an ally's help.

On a pilgrimage, Freydis and her party are savagely attacked. Harald and Leif seek a route through the marshes near London as Edmund is crowned king.

Leif proposes an audacious assault on London, one that Emma and Godwin fear their brash and headstrong boy-king, Edmund, will be too reckless to defeat.

Schemes, betrayals and politics rule the day as a new monarch takes the throne of England. Leif is hailed as a hero but secretly questions his faith.

Freydis returns to Kattegat and joins a sacred order. Canute solidifies his power in England. Kåre revisits the holy site of a childhood trauma.

Olaf makes a pact with Kåre as Kattegat prepares for its defense. In Canute's absence, his father, Sweyn Forkbeard, shares England's throne with Edmund.

Olaf and Kåre gather their forces to invade Kattegat. Palace intrigue over control of England's throne results in an unexpected turn of events.

Harald and Leif help Romanos lay siege at Syracuse. Canute travels to Rome to meet with the Pope. A new arrival in Jomsborg catches Freydis' eye.

Harald fights the Emir for control of Syracuse. Something causes the Jomsborg townsfolk to fall ill. Magnus Olafsson unexpectedly arrives in Kattegat.

As the Byzantine army returns to Constantinople, Leif agonizes over the Syracuse horror. Magnus sails to Jomsborg as Freydis' people begin to heal.

Leif meets an unusual nun on his way to Corfu, Freydis devises a plan for Magnus' imminent arrival and Harald's indiscretion worries his friends.

Freydis reunites with her father, Erik the Red. Leif befriends mapmaker Calinicus, Canute returns to London and Harald gets caught in a bad situation.

Harald sacrifices everything to protect his friends, Canute gathers his sons in Kattegat and Erik tries to convince Freydis to stay in Greenland.

Freydis confronts Erik over his schemes to make her stay, Canute declares a successor and Harald devises an escape plan.

Emma prepares to defend the throne. Magnus and Harald vie to be King of Norway. Unbeknownst to each other, Leif and Freydis both return to Kattegat.