Slip and Sach are in the sidewalk star-gazing business when they see a murder committed in a room at the El Royale Hotel.
After Slip is drafted into the Marines, the rest of the gang volunteers so they can be with him. Sach discovers that the colonel knew his father and he is promoted. During a drill that he is putting the rest of the gang through, they find a soldier left for dead on the side of the road. Slip discovers a playing card next to the marine and traces it to Jolly Joe Johnson's gambling house. They suspect that the gambling house is cheating and set out to uncover the proof.
An electric shock enables Satch to predict numbers, so the Bowery Boys are off to Las Vegas to win enough money at the roulette wheels to let their landlady buy an apartment building. Witnessing his winning streak, some gangsters decide to move in and find out his "system" for beating the odds.
Slip and Sach are working for a local newspaper as a reporter and photographer, respectively. Slip wants to get the goods on a local gambling ring that is fixing sporting events, so he and Sach go undercover to expose the ring.
Slip (Leo Gorcey), Sach (Huntz Hall), Bobby (Bobby Jordan), Whitey (William Benedict) and Chuck (David Gorcey) unsuccessfully try to sell a dilapidated car to a street cleaner for a fabulous amount, so they can get enough money to save Louie's (Bernard Gorcey) Malt Shop. Sidewalk photographer Cathy Smith (Teala Loring) snaps a pictures of three bank robbers as they are fleeing a robbery but when the Bowery Boys and Cathy realize that Sach is also in the photograph, they break into the photo lab to destroy the negative, which might make the police think Sach was involved in the robbery.
Slip invites his cousin Jimmy to stay with his family after he is released from prison. However, Jimmy soon gets mixed up with an auto-theft ring.
The Bowery Boys head west to clear Louie of an old murder charge that he had killed his gold-mine partner. Sach has the map to the gold mine painted on his back, and Blackjack McCoy has him kidnapped by Indian Joe. Gabe poses as a dangerous gunman, the Klondike Kid, while Slip is in charge of all the remaining loose ends.
Slip, Sach and the rest of the Bowery Boys enter a haunted house, where they engage in slapstick with a gorilla, a robot and a vampire
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.