A mysterious man, Julius Slinkton enters the life of Mr. Sampson, the manager of a life assurance office. Well-spoken and with insinuating manners, Slinkton initially seems to be the consummate gentleman. However, as Sampson learns soon enough, appearances can be deceiving. Written in the uncanny style of his close friend Wilkie Collins, this detective story is an unusual treasure in Charles Dickens' writing career.