Brian Cartwright, impecunious adventurer, blackmails four unfortunates unwittingly involved in a crime. As zero hour approaches he invites them all to dine with him; he has received an annonymous and threatening note foretelling his death at this same hour and thus includes Dr Morelle among the guests. The threat materializes, and Morelle sets about discovering the murderer from among the guests. In an exciting climax, during which the murder scene-is re-enacted, the authors finally allow the sleuth to corner his man (or woman?) in which operation he is ably assisted by Miss Frayle and an obliging journalist, also invited to the feast.