It tells of the murder of James Martenroyde, a Yorkshire mill-owner who is about to marry for the second time. His body is found one night near his own home. Suspicion falls on his nephew and the latter's mother. Certainly there was something very strange about their house. Why was it so carefully locked up and what did the detective find there when he broke in? Above all, why was the old woman servant of that house found murdered in exactly the same manner as Mr. Martenroyde? The solution of this ingenious mystery is startling and exciting, satisfactorily completing a singularly well-written thriller in which all the characters are interesting and colorful.