In 1903, Doctor Huntington Bailey meets a friendly older lady during a train trip. She tells him that she is going to visit her brother Nick and his lovely young wife Allida. Once in New York, Bailey hears that his train companion suddenly died. Shortly afterward, he meets the strange couple and gets suspicious of Nick's treatment of his wife.

A private detective is offered a job protecting a rich business man from suspected blackmail. Before he can accept the case a murder is uncovered.

A widow confesses she murdered her husband and kills two more people before her stepdaughter and an attorney prove her wrong.

After one member of their group is murdered, the performers at a burlesque house must work together to find out who the killer is before they strike again.

Young artist Monte Crandell is being sued for an unauthorized caricature. To escape arrest, he disguises himself as a mystic, only to conjure up a genuine ghost during a seance. Things come to a head during his trial, where the invisible ghost takes the witness stand on Our Hero's behalf.

While on shore leave to celebrate his first anniversary, Lt. Peter Duluth (Warren Douglas) takes his wife, Iris (Audrey Long), to a Los Angeles hotel but is turned away. When mysterious Colette (Stephanie Bachelor) offers them her suite, the young couple becomes entangled in a murder plot. Aided by two PIs, Peter and Iris find two corpses and are desperate to locate Colette before she becomes the next victim, but the killers are one step ahead.

Gang Leader Dutch Malone goes on a hunting trip and is in a car wreck and is confined to the hospital, without the knowledge of any of his gang members. District Attorney Brady induces taxidermist Peter Winkly, who is an exact double for Malone,to impersonate Dutch and assume leadership of the gang. Winkly "takes over" the gang and only Rita, Dutch's girl friend, has any suspicion that he is not really Dutch. But Dutch sees a newspaper showing him out on the town, escapes from the hospital and is on his way to look up the impostor.

Jean Loring has her men illegally killing and selling game. Roy suspects her and gets himself invited to stay at her ranch. Investigating he finds the freezer where the slaughtered game are kept. But he is caught, tied up, and left to freeze.

A serviceman returns home at the end of WWII to discover his wife has become the head of her own very successful advertising agency. Comedy.

Secrets of Scotland Yard is Republic's spin on a plotline first elucidated in the old E. Phillips Oppenheim novel The Great Impersonation. After losing WW I, the German high command, with remarkable foresight, prepares for the next war by planting a spy in the British Admiralty. Edgar Barrier plays the dual role of the German spy and his British twin brother. When one twin is killed, the other assumes his identity. The question: is the surviving brother the "good" one or the bad? It is up to C. Aubrey Smith, cast as Scotland Yard inspector Sir Christopher Belt, to sort out the mystery. Though it owes a great deal to the aforementioned Oppenheim yarn, Secrets of Scotland Yard is actually based on a novel by Denison Clift, who also wrote the screenplay.