Based on several stories by Sir Arthur Conan Doyle, this riveting murder mystery finds master sleuth Sherlock Holmes (Basil Rathbone) and his faithful assistant Dr. Watson (Nigel Bruce) trying to solve the case of the "Pajama Suicides." London is rocked by a rash of baffling suicides of wealthy gamblers, but Holmes in inclined to believe that they are premeditated murders. He feigns his own death and assumes the identity of Rajni Singh, a retired Indian officer with a paralyzed arm, so that he can move undetected all around the city. He stalks the city's gaming clubs and eventually meets a mysterious, perfidious woman named Adria Spedding (Gale Sondergaard). To his dismay, Holmes soon falls into Spedding's clutches from which he may never escape...
Based on a Conan Doyle's story "The Six Napoleons," this enigmatic crime thriller follows the investigation of master detective Sherlock Holmes (Basil Rathbone) and his faithful assistant Dr. Watson (Nigel Bruce) when the priceless "Borgia Pearl", a jewel with a sinister reputation for bringing murder to its owner, is stolen from the British Museum in London by master criminal Giles Conover (Miles Mander). The investigation takes a weird turn when a series of ghastly murders begins, and Holmes discovers the link between the two cases.
Puerto Rico has become the back door by which a criminal syndicate smuggles inexpensive contraband diamonds from South America into the United States, dramatically driving down the price of legitimate gems. After they have ruthlessly murdered a special investigator, Moto is assigned to the case. While sailing to the island he impresses Twister McGurk, a slow-witted but amiable wrestler, with his martial arts abilities and gains a loyal friend and bodyguard. When an attempt on his life fails and another government official is murdered, Moto sends authorities a fake telegram identifying himself as a criminal named Shimura and making him and the Twister wanted fugitives. That ploy allows them to infiltrate the gang and expose the criminal mastermind behind it.
A young and handsome archaeologist discovers the crown of the Queen of Sheba, and returns with it to a San Francisco museum where it is put on display. Its safety is in doubt as many criminals want the crown — an international pair of criminals, a San Francisco gangster and his cohorts, and a super criminal known as Metaxa. Mr. Moto is forced to postpone his vacation while he deals with the threat.
A boxer dies in the prizefight ring, and detective Mr. Moto is called in when it turns out to be murder. What Moto uncovers, with the help of Charlie Chan's son Lee, is a gangland gambling racket.
Mr. Moto poses as both an innocuous archaeologist and aged Buddhist mystic in French-ruled Cambodia in order to foil two anti-government revolutionary plots, one by fanatical holy man Bokor, who wants to overthrow the local leader, the self-indulgent Rajah Ali, and Ali himself, who wants to lead an insurgency against French colonial rule. Moto is aided by Vicki Mason, a daring Amelia Earhart-type aviatrix, who doubles as an international agent, and manages to rescue two bumbling newsreel photographers, Chick Davis and Marty Weston, the latter of whom seems to be attracted to the stunningly beautiful Miss Mason.
Mr. Moto has himself imprisoned on Devil's Island so he can help his cellmate (Ames) escape and thereby get the goods on a gang of international killers.
Mr Moto encounters mysterious goings-on on a ship bound for Shanghai. He recognises his steward as the murderer of a man in San Francisco, and catches him trying to steal an important letter from the stateroom of another passenger, Robert Hitchings. Hitchings, son of the owner of the shipping line, falls in love with Gloria, who refuses to tell him anything about her life and disappears when they arrive in Shanghai. In Shanghai, Mr Moto uncovers the secret which links the murder in San Francisco, the mysterious letter, and Gloria.
Mr. Moto finds himself in Peiping seeking ancient scrolls that, placed together, will form a map to the location of Genghis Khan's long-hidden treasure. There are a total of seven scrolls and Moto himself has recently acquired one of these during a foray into Mongolia. The remaining six scrolls are in the possession of Madame Chung and her son, Prince Chung. They very much want to protect the dignity and honor of their ancestors and with Moto's help, try to keep thieves, led by Colonel Tchernov, from getting their hands on the map.
Immigrant radical Bartolomeo Romagna is falsely condemned and executed for a payroll robbery. Years later, his son Mio sets out to find the truth of the crime and to bring to account the gangster Trock Estrella.
Passing through a small town, Joe is arrested for kidnapping. A lynch mob burns down the jail and Joe is believed killed. The incident has been captured on newsreel film and, for revenge, Joe urges his brothers to use the film to prove the mob guilty of his murder.
