The Simpsons' dog, Santa's Little Helper becomes very excited and runs away from home to the dog racing track, where he falls in love with a female greyhound named She's the Fastest. She is given to the Simpsons after her owner notes that she will no longer race after falling in love. One day, She's the Fastest gives birth to 25 puppies. Eventually, the puppies become difficult to manage, and Homer and Marge Simpson attempt to sell them to people more capable of giving them adequate care. After seeing the puppies unwilling to separate, however, people begin to leave. Suddenly, Montgomery Burns arrives and offers to let them live in his mansion. After the Simpsons choose not to sell the puppies to him, he steals them when they are not looking.
Bart and Lisa Simpson track the puppies to Mr. Burns' mansion, where they spy on him through a window. They see him treating the puppies well by giving them a bath. When one of the puppies stands on his hind legs, Mr. Burns picks him as his favorite of the bunch. Burns inexplicably claims that the puppy reminds him of actor Rory Calhoun, and names him "Little Monty". After the bath, Mr. Burns walks into the next room, loads a gun, and sings a musical number called "See My Vest" (a parody of "Be Our Guest" from the 1991 film Beauty and the Beast) while demonstrating his wardrobe of fur clothing to his personal assistant, Waylon Smithers. After his performance, Burns prepares to kill all of the puppies, except for Little Monty, to make a new tuxedo for his wardrobe.
After learning about Mr. Burns' plan, Bart and Lisa sneak through the window and attempt to escape with the puppies down a laundry chute using Bart's socks. However, Mr. Burns is waiting for them at the bottom. As Mr. Burns is about to kill the dogs, Bart grabs Little Monty from Mr. Burns' hands and places him with the other puppies, hoping that Mr. Burns will not kill the dogs if he can not determine which is Little Monty. When Mr. Burns tells Little Monty to stand up, though, he does. As Mr. Burns bends down to pick up Little Monty, Bart reels a clothesline with some socks hanging from it, causing all of the puppies to stand up. Mr. Burns can not tell which is Little Monty, so he prepares to shoot them all. However, the standing dogs are too cute for him to kill and, emotionally touched, he promises to never wear fur or kill any animals that can do an amusing trick. Mr. Burns buys all of the puppies from the Simpsons and successfully raises all of them into world-class championship racing dogs, winning him millions, to Homer's dismay over the Simpson's missed fortune-making opportunity.