The cave of Lascaux may be closed to the public, but five scholars a day are allowed inside, and Nora Barnes has finagled an appointment. True, she may have fudged a bit in her letter to the authorities, but she does teach art history, and she isn't about to miss her chance to see the world's most famous prehistoric paintings. During a tour of the cave, another visitor is murdered. When the local inspector pegs Nora as a suspect, she embark on a mission to solve the crime.