Book excerpt: It was not altogether surprising that Ambrose Brenthurst was found brutally murdered outside Fountain Court the night he had presided over the diner meeting of the 'Hernshaw Thirteen Club'. Many were the potential murderers - some of them guests at the diner. But when a second murder takes place it precipitates a crisis in which investigator Sir Clinton Driffield must penetrate a maze of conflicting evidence to spot the murderer.