Ten strangers are invited to Soldier Island, an isolated rock near the Devon coast. Cut off from the mainland, with their generous hosts Mr. and Mrs. U.N. Owen mysteriously absent, they are each accused of a terrible crime. When one of the party dies suddenly they realise they may be harbouring a murderer among their number. The 10 strangers include a reckless playboy, a troubled Harley Street doctor, a formidable judge, an uncouth detective, an unscrupulous mercenary, a God-fearing spinster, two restless servants, a highly decorated general, and an anxious secretary. One by one they are picked off. Who will survive? And who is the killer?