While investigating a secretive group of aristocrats, Sherlock Holmes (Reginald Owen) and Dr. Watson (Warburton Gamble) must contend with a number of murders related to the elite society. Suspects involved in the case include lawyer and socialite Thaddeus Merrydew (Allan Dinehart) and Mrs. Pyke (Anna May Wong), the widow of a deceased group member. The stakes become higher when the lovely Eileen Forrester (June Clyde) is targeted by the killer and seeks the protection of Holmes and Watson.