In this novel, Dr. Thorndyke builds a card house of wild speculations to solve a perplexing murder case, astonishing all observers, including the police. The victim is Julius D ’Arblay, an artist highly skilled at the rare French art of making wax-work figures and portrait masks. D’Arblay has a beautiful daughter, which leads to a romance with a young Dr. Grey who discovers the father’s body and brings the case to Dr. Thorndyke’s attention. Before the end of the story, the young doctor and his love will each have survived two murder attempts by an increasingly frantic killer. There are lots of great scenes: stalking scenes, vicious attacks on Dr. Gray and Marion with various weapons, a sinister scene in a dense yellow London fog, a humorous exhumation of a dead man of dubious identity, and very funny vignettes with a tippler of an old doctor advising Gray on how to handle troublesome patients. Thorndyke’s lovable lab assistant Polton has a starring role in this novel.