Lost Caverns Hotel bellhop Freddie Phillips is suspected of murder. Swami Talpur tries to hypnotize Freddie into confessing, but Freddie is too stupid for the plot to work. Inspector Wellman uses Freddie to get the killer (and it isn't the Swami).
A letter is addressed to three wives from their 'best friend', announcing that she's running away with one of their husbands – but she doesn't specify which one.
Virginia Cunningham is confused upon finding herself in a mental hospital, with no memory of her arrival at the institution. Tormented by delusions and unable to even recognize her husband, Robert, she is treated by Dr. Mark Kik, who is determined to get to the root of her mental illness. As her treatment progresses, flashbacks depict events in Virginia's life that may have contributed to her instability.
Leona Stevenson is confined to bed and uses her telephone to keep in contact with the outside world. One day she overhears a murder plot on the telephone and is desperate to find out who is the intended victim.
After a whirlwind romance in Mexico, a beautiful heiress marries a man she barely knows with hardly a second thought. She finds his New York home full of his strange relations, and macabre rooms that are replicas of famous murder sites. One locked room contains the secret to her husband's obsession, and the truth about what happened to his first wife.
A gang of criminals, which includes a piano player and an imposing former convict known as 'Gruesome', has found out about a scientist's secret formula for a gas that temporarily paralyzes anyone who breathes it. When Gruesome accidentally inhales some of the gas and passes out, the police think he is dead and take him to the morgue, where he later revives and escapes. This puzzling incident attracts the interest of Dick Tracy, and when the criminals later use the gas to rob a bank, Tracy realizes that he must devote his entire attention to stopping them.
Sandra Carpenter is a London-based dancer who is distraught to learn that her friend has disappeared. Soon after the disappearance, she's approached by Harley Temple, a police investigator who believes her friend has been murdered by a serial killer who uses personal ads to find his victims. Temple hatches a plan to catch the killer using Sandra as bait, and Sandra agrees to help.
When his best friend is murdered inside a London dancehall, a cab driver and his girlfriend involve themselves in the investigation and discover a major criminal operation hiding behind the club's friendly facade.
Maisie Revere, a showgirl stranded in Los Angeles, decides to join the local police department on the persuasion of Lieutenant Paul Scott who wants to use her as an undercover agent to expose a conman.
When a kindly priest is murdered while waiting at a street corner in a quiet Connecticut town, the citizens are horrified and demand action from the police. All of the witnesses identify John Waldron, a nervous out-of-towner, as the killer. District Attorney Henry Harvey is then put on the case and faces political opposition in his attempt to prove Waldron's innocence.
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.