Sean Russell, a Boston teen, has signed on as seaman on a convoy to Liverpool. His ship is torpedoed by a German submarine, and he’s washed ashore on the coast of County Mayo, the only survivor. His best friend has been drowned.
He is nursed back to health by the Connolly family, fishermen who live outside the law. As he recuperates, he meets Sally, the daughter of the local policeman, which alienates the Connollys. Sean does his best to remain his ties with them, though, because he plans revenge for the loss of his friend, and they could be useful.
Meanwhile, yet another German agent has been dropped into Eire to replace the others who have been caught and imprisoned. This one, cold and brutal, is determined to show his worth to his superiors, and he contacts the Connollys with a plan of his own.
This provides Sean his opportunity, but a neutral country at war with itself has its own minefields, and he finds himself in the middle of one.