Years have passed since the events of the last season, and King Edward is still forging ahead with his ambitions to unite the Saxon Kingdoms to fulfil his late father's dream. Although a long-standing peace between Danes and Saxons now exists, that harmony is under threat. Not only by a new Danish invasion but a Saxon rebellion. Uhtred has been entrusted with protecting Edward's illegitimate son, the future King of England, Aethelstan. But the treacherous Lord Aethelhelm has ambitions for his grandson Aelfweard, Edward's other son, to rule.

We follow Uhtred as he faces his greatest enemies, and suffers immeasurable loss, on his quest towards fulfilling his destiny. Meanwhile, Edward treads a fine line between peace-keeper and authoritarian as he battles to bring together the fractured Kingdoms of the land. In a surprising twist of fate, Uhtred discovers that the quest to unite England may well be linked to his own personal destiny.

As Edward and Aethelflaed spar over the future of Mercia and their father's dream of a united England, Uhtred tries to recover his lost birthright.

England, 872. A Saxon man, raised by Danes, must choose a side and play his part in the birth of a nation, alongside the man who would become known as King Alfred the Great.