A man wins $50,000 in a card game with gamblers, but is soon found dead and the money missing. Slip and Sach find the money near where the body was discovered, and soon find themselves the target of both the police and the gamblers.

Sach just lost his job as an assistant to a private detective, but he wasn't paid. Slip goes with him down to the detective's office to demand payment, but finds the office empty. A woman enters the office and mistakes Slip for the detective and convinces him to take on a case to find her sister after offering a $50 retainer.

Slip and the gang stray from newspaper work to detective work.

Sach is given a post-hypnotic suggestion that turns him into a championship prizefighter.

The Bowery Boys--Slip, Sach, Bobby, Whitey & Chuck--start their own exterminating service, and get a job which takes them to a spooky old abandoned mansion in the middle of the night. Meeting up with pal Gabe and his new French bride, the boys are tormented by mad scientists who try to convince them the place is haunted and then kidnap Sach in order to place his brain inside a gorilla.