Four friends, wanting to adopt a puppy named Penny, calculate that they can easily afford her dog food and raise money for other supplies by baking and selling doggy treats.
Mister Bud, the family dog, has a satisfying routine to his life, but when another dog joins the family and disrupts his schedule, Mister Bud must learn to adapt.
First Shaggy and Scooby investigate a Romanian foreign exchange student whom they believe to be a werewolf, and then the friends travel to Hawaii to take part in a bicycle race, only to be confronted by a tiki figure threatening doom.
As the gravedigger tells his wife how a band of cats marched into the cemetery to mourn their dead king, their own cat, Old Tom, listens with a strange intensity.
When Sam the cat becomes too big to fit through the cat flap, the Robinson family realizes that even though they have been feeding him, they have neglected him in other ways.