A prison trustee rescues a despondent executioner from a bar-room brawl, and is blamed for the fight by a tabloid reporter who actually started it, and loses parole, becomes embittered, and gets blamed for murder of guard.

An undercover agent wrongly punished for murder is paroled to a remote tropical island with a diamond mine slave labor run by a sadistic foreigner.

"The Unknown" was the final entry in Columbia’s I Love A Mystery series. A woman hires two detectives to keep her alive long enough to claim her inheritance.