Fifth Avenue socialite Irene Bullock needs a "forgotten man" to win a scavenger hunt, and no one is more forgotten than Godfrey Park, who resides in a dump by the East River. Irene hires Godfrey as a servant for her riotously unhinged family, to the chagrin of her spoiled sister, Cornelia, who tries her best to get Godfrey fired. As Irene falls for her new butler, Godfrey turns the tables and teaches the frivolous Bullocks a lesson or two.

When the ancient continent of Mu sank beneath the ocean, some of its inhabitant survived in caverns beneath the sea. Cowboy singer Gene Autry stumbles upon the civilization, now buried beneath his own Radio Ranch. The Muranians have developed technology and weaponry such as television and ray guns. Their rich supply of radium draws unscrupulous speculators from the surface. The peaceful civilization of the Muranians is corrupted by the greed from above, and it becomes Autry's task to prevent all-out war, ideally without disrupting his regular radio show.

Capricious small-town girl Juliette and barge captain Jean marry after a whirlwind courtship, and she comes to live aboard his boat, L'Atalante. As they make their way down the Seine, Jean grows weary of Juliette's flirtations with his all-male crew, and Juliette longs to escape the monotony of the boat and experience the excitement of a big city. When she steals away to Paris by herself, her husband begins to think their marriage was a mistake.

After a detective is assaulted by thugs and placed in an asylum run by Professor Baum, he observes the professor's preoccupation with another patient, the criminal genius Dr. Mabuse the hypnotist. When Mabuse's notes are found to be connected with a rash of recent crimes, Commissioner Lohmann must determine how Mabuse is communicating with the criminals, despite conflicting reports on the doctor's whereabouts, and capture him for good.

Betty Boop goes to see the fearsome Old Man of the Mountain for herself; he sings the title song and a duet with Betty.

The villainous Dr. Fu Manchu races against a team of Englishmen to find the tomb of Ghengis Khan, because he wants to use the relics to cause an uprising in the East to wipe out the white race.

A circus' beautiful trapeze artist agrees to marry the leader of side-show performers, but his deformed friends discover she is only marrying him for his inheritance.

A tramp falls in love with a beautiful blind flower girl. His on-and-off friendship with a wealthy man allows him to be the girl's benefactor and suitor.

The murders start with the body of Robin. He is found with a arrow through the heart, but Vance deduces that the body was placed and not found where he was killed. The note found dealing with the murder was part of a nursery rhyme and signed by 'Bishop'. The only witness may have been Mrs. Drukker and Adolph, but they are not talking. As the murders progress, each one is accompanied by a nursery rhyme. It is up to Philo Vance to unravel the clues and unmask the identity of the murderer 'Bishop'.

Thymian Henning, an innocent young girl, is raped by the clerk of her father's pharmacy. She becomes pregnant, is rejected by her family, and must fend for herself in a harsh, cruel world.