Fred Martin, a taxi driver who is a reformed convict, is used by the police to go undercover in order to help catch a gang of safe robbers. However things start to go wrong when the police stake out the wrong bank and Fred finds himself alone with the crooks.

When his wife stops writing to him and his letters are returned unanswered, Dan becomes extremely concerned about her welfare. He returns home but is only able to meet with her briefly before she is found murdered. Dan is the obvious suspect but has only 36 hours to find out who murdered her. In so doing he uncovers a shocking catalogue of his wife's past affairs and an identity that he knew nothing about.

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