This is the true story of Aethelflaed, the 'Lady of the Mercians', daughter of Alfred the Great. She was the only female leader of an Anglo-Saxon kingdom. It is the tale of one family, two kingdoms and a common enemy. Born into the royal house of Wessex at the height of the Viking wars, she is sent to her aunt in Mercia as a foster-child, only to return home when the Vikings overrun Mercia. In Wessex, she witnesses another Viking attack and this compounds her fear of the enemy. She falls in love with a Mercian lord but is heartbroken to be given as bride to the ruler of Mercia to seal the alliance between the two Anglo-Saxon kingdoms. She must learn to subjugate her feelings for her first love, overcome her indifference to her husband and win the hearts of the Mercians who despise her as a foreigner, twice making an attempt on her life. When her husband falls ill and is incapacitated, she has to learn to rule and lead an army in his stead and when he subsequently dies, she must fight to save her adopted Mercia from the Vikings and, ultimately, her own brother.