Slip and Sach take the rap for a robbery they did not commit in order to uncover the real robbers, whom they suspect are led by a convict who gives orders to his gang outside via a short-wave radio stashed somewhere in the prison.
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.
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 has entered the Boys' rattletrap car in a souped-up jalopy race, but has no chance of winning until Satch, with the aid of a scientist acquaintance, comes up with a chemical concoction that acts as a super-fuel; but a rival entrant in the race learns of this and tries to get the formula for himself.
After being punched in the nose, Sach finds out that he has the ability to read minds. Slip and the gang start up a detective agency try to cash in on Sach's new powers.
When Sach eats too much sugar, he goes into a trance whereby he's able to predict the future. Slip tries to make some money off of Sach by using him as a fortune teller in a carnival, until a mad scientist kidnaps Sach to use him in an intelligence-switching experiment with a monster.
Slip, Sach and the gang (Bowery Boys) think an air-raid test is for real and join the Army.
Slip and Sach (Bowery Boys) go to prison to help a reporter with a story.
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 is the exact double of a famous French scientist who has invented a powerful rocket fuel. Enemy agents, mistaking Sach for the scientist, attempt to kidnap him and get the formula for the fuel.
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.
Slip gets fired from his job at a construction company for decking his boss. His sister, who got him a job at the company, is angry with him. Slip manages to get a job with the District Attorney serving warrants, as does Sach. Through his job, Slip finds out that all is not quite kosher at his old construction company, and that his sister may be in danger.
Sach receives news that he is the heir to the Terwilliger Debussy Jones fortune. Accompanied by his pal Slip, he arrives at the Jones mansion to review the legal papers needed for him to claim his new fortune. However, Sach and Slip discover that the rightful heir, the young Terwilliger III, is being cheated out his inheritance by the miscreant duo of Stuyvesant Jones and Clarissa. Sach and Slip, with the help of their fellow Bowery Boys, save the day and restore the heir’s inheritance.
The Bowery Boys join the Navy to catch some crooks who are posing as sailors.
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 the gang (Bowery Boys) foil foes of the exiled, incognito king of Truania (Sig Ruman).
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 (Bowery Boys) open a nightclub after Sach has his tonsils out and wakes up with a singing voice.
A ghost helps the Bowery Boys capture a gang of crooks led by a mad doctor.