Slim Callaghan is called to Devonshire to investigate a burglary at Margraud Manor, where valuable jewels - heirlooms of the Vendayne family insured for £100,000 - have disappeared. With his assistant, Windermere Nikolls, he discovers some startling facts - particularly about the lovely Esme Vendayne - and the mystery leads Callaghan to a shady London nightclub and a violent underworld.