Ma and Pa Kettle are awarded an all-expenses-paid trip to New York City after Pa wins yet another radio jingle contest for the horrid-tasting Bubble-O beverage. With no one to look after their new home in Cape Flattery, Washington, and their wild brood of fifteen children, the two are about to turn down the prize until Pa discovers fugitive bank robber, "Shotgun" Mike Munger, sleeping in their former, run-down house. Needing a hideout, Munger claims to be a poet named Jones and offers to baby-sit the children while Ma and Pa are away. In turn, Munger asks the naïve Kettles to deliver his "empty" bag, filled with $100,000 in stolen money, to his "brother" Louie. Arriving in New York, Ma and Pa are met at Central Station by their daughter-in-law Kim, and while getting a taxi, Munger's bag is accidentally taken by the chauffeur of investment broker Harold Masterson. When Little Joe arrives at the Waldorf-Astoria to pick up the money, the Kettles tell him the bag is still at the station, so he and the other gangsters assume that Pa has discovered the bag's true contents. Meanwhile, Munger is having little luck in handling the Kettle children, let alone their modernized home, but he refuses any offers of help, fearful that his true identity might be exposed. Back in New York, the Kettles keep buying new bags to replace the missing one, only to have each stolen by the Munger gang. Later, while Ma is getting a complete beauty make-over, Pa meets Louie at the zoo, where he is arrested and falsely accused of feeding poisoned peanuts to the monkeys. With the help of the Kettles' oldest son Tom, the police finally connect the Kettles' stolen bags with the Munger gang, and they convince the young man to cooperate in helping them capture the gangsters. Meanwhile, Masterson finds the missing bag among his luggage, and thinking that Pa is C. P. Kettle, a multimillionaire clothing manufacturer, invites him to a high society party. Back in Cape Flattery, the police arrive at the Kettle home to arrest Munger, only to discover that they are actually rescuing him from the Kettle kids. The rest of his gang is captured by the police at Masterson's party, when they make one final, futile attempt to acquire the bag. Ma and Pa Kettle then return home, where they rescue the two police who have had the misfortune of being left behind by the sheriff to care for their clan.