Preteen Moochie Daniels just wants a dog, but his dad, Daniel, is allergic to canines, like Bundles, the shabby sheep dog of neighbor Charlie Mulvihill who secretly trained his pet to help him steal jewels. Mooch`s big brother Wilbert `Wilby` is smart, shy and a promising inventor, but hopelessly clumsy when it comes to girls, and is jealous of his slick mate Trey who has no problems. Desperate Wilby resorts to a spell from the ring of Lucrezia Borgia (he accidentally got from dad`s museum of curiosities), which magically turns him into Bundles and back at uncontrollable times. This is how he also knows that the diamond on loan in his father`s museum is Charlie`s next target, but who would believe his story?