Middle-aged ship's bosun George is about to marry young and pretty Louella. Her former lover, Skip Clark, is jealous; when George turns up dead, Skip is the chief suspect. Blackie believes Skip is innocent; George was killed for his money.
Phantom Burglar steals Lenore Aldwin's important documents; she offers $500 reward for their return. Crooks want 10 to 20 times that amount of money. Boston Blackie is determined to find out what was so important in those stolen letters.
A small time pickpocket runs afoul of what looks like a sweet old lady in old fashioned clothes with a comically old automobile, but is in fact a ruthless head of a crime ring. He's shot and put into a coma. Blackie senses the lady, a known ex-con, is up to something as she and her mob plan an art museum heist.
Blackie aids a man accused of hit and run. The only clue to what really happened is a Hollywood designer dress.
The husband of a friend Mary's is accused of being the inside man on a bank robbery. Blackie seeks the truth
A blackmailer is killed by a poisoned needle when he opens a spring-loaded box sent to him through the mail. A local florist admits to the crime, but Boston Blackie doesn't believe it.
Barney Stevens, an East Coast bank robber, escapes from prison and skips to LA with his partner, Dave Brubaker. However, he is recognized by a bank teller before committing a new robbery. Stevens is arrested, and Brubaker seeks revenge - by killing the teller. The teller's wife sees the shooting, and Brubaker determines to get her too. Luckily, she is a friend of Boston Blackie.
Blackie has his doubts when a hired farmhand, who was recently released from a mental hospital, is accused of attempting to murder a farm couple.