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.