After transforming a football into a toaster and a cat into a canary, Sydney's new invention creates unexpected problems by changing Sydney into his dog and his dog into Sydney.
Most of the people who take one of the twelve pups Mr. Mullin is giving away want a dog to perform some sort of task for them, but the little boy just wants a pet to love.
When the dog explains what he knows to the animals in the deep dark woods who know nothing of people, they laugh at him so hard he goes to live with man forever.