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. The 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. When one of the party dies suddenly they realise they may be harbouring a murderer among their number.

The tension escalates as the survivors realise the killer is not only among them but is preparing to strike again… and again…