It is 1971 when Sean, a Boston Southie, travels from the US to Ireland. On his last night there, he accepts a dare to sleep in an ancient burial cairn. When he awakes, he believes he is only dreaming again and will wake up soon. Finally he realizes he has dream-traveled to the 1440s, but does not know how to get back home. Survival skills he learned from the Irish Mob and use of medieval weaponry from his university professor serve him well. He soon finds himself in a street fight with the Captain of the Guards - and wins. The Clann Chieftain learns about him and offers him a position. Sean, now Sheín, must protect the family, household, castle and villagers from ever-present danger. He discovers that his Future Past is finally here, where he finds both his purpose and the love of his life.