When Mrs Paxton, related to the aristocratic Leigh family of Sussex, is found poisoned in her bedroom one morning, fingers point towards her artist nephew Terence Napier, seen leaving the house earlier that previous evening after a row over her will. Months later and Napier has never been found, but curiously a dead body is discovered in a train compartment, and scattered at the dead man's feet are the famous Leigh sapphires – a necklace owned by Mrs Paxton, but destined to go back to the Leighs in the event of her death.
Scotland Yard once again call upon the services of author Jack Haldean to help solve this most complicated of cases. Soon there are links to a serial thief and murderer, known as the The Vicar, and it seems there is more to this case than a family feud over inheritance.