Chan, in Paris for a reunion with friends from World War I, becomes involved in investigating the murder of a munitions manufacturer who was supplying arms to the enemy, even as the rising clouds of World War II force the city into nightly blackout status..

Opera singer Renee Dupree is in love with struggling composer Julian who falls very seriously ill. She goes to impresario Mueller for the money Julian needs but is saved from sacrificing her virtue when a jealous lover kills Mueller.

Billy Morrow (Ben Lyon), who comes from a wealthy family, is sailing to Europe with his father (Holbrook Blinn) on their yacht. Along for the ride is Mrs. Parr (Claire Eames) and her stepdaughter. Near the French coast, Billy discovers that Mrs. Parr wants to arrange a marriage between him and the girl, so he escapes and takes a lifeboat ashore.

Locals in an Italian village believe evil has taken over the estate of a recently deceased pianist where murder has taken place. The alleged killer: the pianist's severed hand.

After a series of murders, a man finds out that his mother was bitten by a vampire bat during her pregnancy, and he believes that he may be the vampire committing the murders.

Respected Parisian banker Paul Lavond is framed for robbery and murder by crooked associates and sent to prison. Years later, he escapes with a friend, a scientist who was working on a method to reduce humans to a height of mere inches (all for the good of humanity, of course). Lavond, however, is consumed with hatred for those who betrayed him, and takes the scientist's methods back to Paris to exact painful revenge.

On the night before he sails in search of the steamship Arcadia's sunken gold, Paul Sinclair (Bruce Bennett)meets Madeliene Nielson (Anita Louise) in a San Francisco nightclub. On the second day at sea, Madeliene turns up as a stowaway. While diving and searching for the sunken gold, off the Phillipines, Paul discovers that a foreign-country submarine has been laying mines in order to completely cut off the Phillipines from American protection.

After intrepid working girl Mary Carter becomes the new owner of a reputedly haunted mansion located off the Cuban coast, a stranger phones warning her to stay away from the castle. Undaunted, Mary sets sail for Cuba with a stowaway in her trunk—wise-cracking Larry Lawrence, a radio announcer who helps Mary get to the bottom of the voodoo magic, zombies and ghosts that supposedly curse the spooky estate.

Dr. Peter Blood, unjustly convicted of treason and exiled from England, becomes a notorious pirate.

The Falcon travels to Mexico where he gets involved with murder and a mysterious painting.