At a costume party with the dubious theme of 'famous murderers and their victims', the know-it-all amateur criminologist Roger Sheringham is settled in for an evening of beer, small talk and analysing his companions. One in particular has caught his attention for her theatrics, and his supposition that she might have several enemies among the other guests proves true when she is found hanging from the 'decorative' gallows on the roof terrace... A British Library Crime Classic.