An adaptation of the story by Sir Arthur Conan Doyle about a very wealthy businessman with a strange secret. Sherlock Holmes investigates the disappearance of a missing husband who is traced to an opium-den in Wapping, where the proprietor denies knowledge of him. Holmes finds him upstairs in a pool of blood, is attacked and fights his way out. After various enquiries he solves the mystery. Originally the pilot for a proposed television series, this film ended up as a B-movie short.