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 of 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.
Slip and Sach are working as cleaners in a high rise building. They enter an office to clean it when a messenger hears them use Slip's given name, Terrance Mahoney. The messenger has a letter for "Terrance Mahonoey, Esq." and mistakenly delivers it to Slip. The letter informs Slip that he has inherited a mansion in Long Island. The boys then make their way to the mansion and find that it is inhabited by diamond smugglers. The real owner of the house shows up and helps save the day and defeat the smugglers and gives the boys the house as a reward.
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 Sach's boss, David J. Thurston, has allegedly committed suicide. Slip finds a book of matches with the name of a local nightclub on his boss' desk and finds out from Gabe that a gambling casino is being run out of it. Slip comes to the conclusion that the club had something to do with his boss' death and sets out to find his murderer. The boys get jobs at the club and Louie poses as a rich cattlemen as they gather the information to convict the murderers.
The boys are working at the local boxing arena where their friend, Jimmy Higgins, is boxing. During a crooked match Jimmy is killed. The boys seek out his older brother, Johnny, a former boxer who gave up the sport rather than go crooked, and help train him to get back in the ring. They try to get him a shot at the title, and when they do the same crooked gangsters that were behind Jimmy's death try to get Johnny to take a dive.
The Bowery Boys find a lamp that has strange magic powers.
The Bowery Boys come to the rescue when a corrupt taxi company puts the squeeze on several independent drivers.
Sach and the gang baby-sit a bratty TV star.
Slip and the gang foil foes of the exiled, incognito king of Truania.
Slip and Sach go to prison to help a reporter with a story.
Sach and the gang (Bowery Boys) find stashed cash in an old farmhouse apparently haunted.
When one of the Boys agrees to be hypnotized, he discovers he led a past life in the 1600s as a British tax collector.
The boys buy a uranium mine out west, but when they get there they find that it's pretty much worthless. However, the local badmen are distrustful of these new strangers, and when they mistakenly get the impression that the mine is loaded with uranium, they hatch a scheme to get rid of the boys and take over the mine.
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.
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 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, 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
Slip, Sach, Bobby, Whitey and Chuck 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 Malt Shop. Sidewalk photographer Cathy Smith 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.
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.
A ghost helps the Bowery Boys capture a gang of crooks led by a mad doctor.