Colonel Arthur and Dolly Bantry wake up to the news that a body has been found in their library. She is soon identified as Ruby Keene, a dancer at the Majestic in Danemouth, a seaside resort. Dolly takes her friend, Jane Marple, to the Majestic and together they work to solve the mystery.

While the investigation centres on the Jefferson family and their entourage, Miss Marple's hunch about a second killing proves all too tragically justified.

Concluding part of an adaptation of Agatha Christie's novel. Miss Marple is convinced that the death of schoolgirl Pamela Reeve holds the key to the mystery of the double murder.