Someone announces a future murder by placing a notice in a local paper. When the time arrives, many of the townsfolk gather thinking it's a prank, but someone dies. Fortunately, Jane Marple is visiting a spa nearby, and can advise Inspector Craddock on where to look first.

Inspector Craddock gathers more clues, and uncovers a link to the mysterious sister and brother Pip and Emma. Do they live abroad, or in Scotland, or in Chipping Cleghorn? Meanwhile, Miss Marple is able to learn information that people wouldn't tell a policeman.

Inspector Craddock is alarmed to find that Miss Marple has gone missing - has she become another victim of the murderer?