The Mystery of the Spanish Chest — Agatha Christie

Major Hastings and Hercule Poirot are not interested in the mystery of the Spanish Chest, which has been reported in the papers so often that it seems to be an entirely closed case. But, when Hastings persuades Poirot to attend a fabulous party given by Lady Chatterton, they discover someone sequestered upstairs who is desperate for their help. Will the contents of a dead man's pockets reveal to the inscrutable eye of Hercule Poirot who the culprit is?