Stricken with arthritis, Miss Jane Marple has packed herself off, at the insistence of her nephew, for some rest and relaxation at a resort in the Caribbean. The sea is sublime and the weather is fine in this quiet paradise so far away from bustling St. Mary Mead. But suddenly the calm is interrupted by the death of Major Palgrave, one of her fellow guests at the hotel.
Miss Marple finds herself quite disturbed by this turn of events. She'd just spent the previous evening speaking with the major, who'd seemed to her to be in perfectly good health. He'd been telling her about a photograph that he had--"a snapshot of a murderer?," he'd claimed. Convinced that the major's death was not at all natural, she begins to ask difficult questions. It soon becomes clear that a murderer is lurking among her companions at the hotel, and it is up to Miss Marple to root this person out before he or she can strike again.