It's love at first sight when Beethoven meets Missy, a female St. Bernard, in the park. He helps her escape from her owner's ex-wife Regina and her boyfriend Floyd, who plans to use Missy as a tool to negotiate for more alimony. A few months later, the Newton kids track Beethoven to the basement of Regina's building, where Missy has given birth to puppies. The kids get Beethoven and the pups away just before Regina finds Missy. Regina wants the puppies back after she learns that they're worth a lot of money. Though the kids try to keep the puppies a secret, skipping school in order to keep them fed, Mr. and Mrs. Newton find out about them. Reluctantly agreeing to keep them, Mr. Newton takes the family on a Fourth of July camping trip. Little does he know that Regina and Floyd are staying nearby.