When Farmer Buzzard's collie, Kay, has four puppies, he doesn't know what to do. Three are fine puppies which he can sell, but the fourth is the ugliest puppy ever. No one wants to buy him and, as he grows, it becomes clear he'll never make a sheepdog - and he certainly isn't house-trained! Farmer Buzzard is too kind-hearted to get rid of Smasher, and eventually, when a burglar calls, the big dog has a chance to prove his worth.
