Used. A fete at a country house in Devon, and the well-known thriller-writer Ariadne Oliver has organized a Treasure Hunt with a difference - a Murder Hunt. But Mrs. Oliver feels, unaccountably, that all is not well, and she calls in that celebrated detective M. Hercule Poirot, ostensibly to give away the prizes. And her fears are justified when the body" is found - this corpse is very dead.