Beethoven, a havoc-causing Saint Bernard, tries the patience of his owners, the Newton family, and is surreptitiously sent to dog obedience school by children Brennan (Joe Pichler) and Sara (Michaela Gallo). After Beethoven gets loose during a walk, he changes place with Michelangelo, an identical-looking dog with impeccable manners who belongs to the snobbish Sedgewick family. Both households are utterly baffled by the switch, and order won't be restored until the mistake is rectified.