It was not altogether surprising that Ambrose Brenthurst was found brutally murdered outside Fountain Court the night he had presided over the dinner meeting of the 'Hernshaw Thirteen Club'. There were a good many potential murderers - some of them guests at the dinner. 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.

Partly based on the bizarre 1891 Achet-Lepine murder case in France.