Michael Mason, a former government assassin living in self-imposed exile on a remote Scottish island, spends his days in quiet isolation with only his dog for company. His peace is shattered during a violent storm when he rescues a young girl, Jessie, from a shipwreck that claimed her uncle's life. As Mason nurses her back to health, his heroic act inadvertently alerts his former MI6 handlers to his location. Soon, the island becomes a battlefield as a elite black-ops hit squad is sent to eliminate Mason and everyone in his path. Forced back into the world of violence he tried to leave behind, Mason must use his lethal skills and intimate knowledge of the rugged terrain to protect Jessie and take down the agency that betrayed him.