Dean Jones and Suzanne Pleshette star in this Walt Disney family comedy as Mark and Fran Garrison, a dog-loving couple with different tastes in canines. When their dachshund gives birth to puppies, kindly veterinarian Dr. Pruitt (Charlie Ruggles) convinces Mark to take a Great Dane puppy home with him. The Great Dane, named Brutus, grows up with the tiny pups convinced that he's also a dachshund. Brutus's confused identity sets the stage for a number of mildly comic bits -- he chases policemen up trees, destroys Mark's studio, and ruins a garden party. Fran finally tells Mark that Brutus has to go, but changes her tune when Brutus saves Fran's favorite dachshund puppy, Chloe, from a scrap heap. When Fran announces that she is entering Chloe in a dog show, Mark secretly enters Brutus in the same contest in an effort to convince Brutus to think like a Great Dane.