Wilby Daniels is constantly misunderstood by his father, Wilson. Wilson thinks Wilby is crazy half the time because of his elder son's often dangerous inventions. As a retired mailman who often ran afoul of canines, he has a hatred of dogs, and he can't understand why his younger son, Montgomery "Moochie" wants a dog so badly. Wilby and his self-centered rival Buzz Miller take a new French girl, Francesca Andrassé, to the local museum. Wilby gets separated from the other two, who leave without him. Wilby ends up in a new wing, where he encounters former acquaintance Professor Plumcutt (whose newspaper Wilby used to deliver), who tells him all about mystical ancient beliefs, including the legend of the Borgia family, who used shape-shifting as a weapon against their enemies. On the way out, Wilby collides with a table of rings, ending up with one in the cuff of his pants which he finds later. It is the cursed Borgia ring, and when he reads the inscription on it, he turns into Chiffon, Francesca's shaggy Bratislavian sheepdog. Confused about what has happened, Wilby as a dog goes to Professor Plumcutt, who says he has invoked the Borgia curse upon himself, which can only be broken through a heroic act of selflessness.