Dr. John Watson treats a patient who has lost a thumb. The patient says that the loss of his thumb was not an accident but the result of an attack. However, he fears that the story behind the loss of his digit is so strange that the police will not believe it.
A decadent tale of drugs and the London underworld the cosseted daughter of a respectable businessman - in fact head of a cocaine racket - succumbs to the pleasures of drink and drugs. Vivid nightlife scenes recreate the interwar world of flappers and hedonists; the dapper club owner and seedy street dealers.