Five friends get together to share a delicious dinner, listen to music and dance a little. They have fun and enjoy without excesses or drunkenness. The next morning, the butler is surprised to see a large red stain on the carpet on which an old Spanish chest is resting. When he lifts the lid of the furniture, he discovers to his horror that inside is the corpse of one of the guests, Mr. Clayton, with a dagger stuck in his neck. Hercule Poirot is summoned to help the attractive Mrs. Clayton unravel this strange mystery.