A lawyer who is planning to run for District Attorney accidentally kills a gangster who owns the nightclub where the attorney's girlfriend is a singer. Although he manages to cover up his involvement in the crime, his girlfriend discovers the body and is subsequently charged with the murder.

Special investigator Duke Martin is in London to investigate the authenticity of a rare postage stamp called the Barbados Overplate. Someone is willing to commit murder to get his or her hands on the stamp, which puts a crimp in Duke's efforts to romance every beautiful woman he meets.

Suave private investigator Norman Conquest intercepts a secret message and meets a beautiful but foreign blonde lady in room 605 of the Park Plaza hotel. But when Conquest wakes up in the room the next morning he is lying next to a dead body. With the mysterious blonde nowhere to be seen, Conquest soon becomes the police s number one suspect with Inspector Williams following his every move. In order to clear his name, Conquest enlists the help of Pixie Everard (Joy Shelton), but the going gets rough when he discovers that the murder is connected to a stash of stolen diamonds. As gun-happy gangs of communists and Nazi sympathizers turn up the heat, Conquest has to solve the murder whilst staying one step ahead of both the gangs and the police.

A cab driver nearly hits a man with amnesia, then helps him unravel his past, only to discover he's a murder suspect as she falls for him.

When Johnny Matlock whisks away a cold war secret from under the noses of Berlin's top secret agents, his every move is followed when he returns to England. His girlfriend Paula is kidnapped but her handbag is discovered at the scene of the crime by the aristocratic private eye, Duke Martin. Inside it he discovers the secret formula that the agents are searching for and tracks down her sister Paula. As Johnny grows frantic for the safe return of his girlfriend, Duke Martin plays a deadly game of double bluff with the enemy agents.

Conniving Broadway starlet Mida King has plenty of enemies, so when she's found murdered at Grand Central Station, Inspector Gunther calls together a slew of suspects for questioning. Mida's shady ex-flame, Turk, seems the most likely culprit, but when smart-mouthed private eye Rocky Custer -- also a suspect himself -- begins to piece together the crime, a few clues that Gunther has overlooked come to light.

Discharged by his employer, a private eye stays on a jewel theft case after a model with information for him is murdered.

Ships disappear on route across the Arctic Sea, and a special submarine is sent to investigate.