More than anything, Benjamin Ravenspell wants a pet. But when he buys a mouse named Amber, he gets more than he bargained for. No sooner does Ben take her home, than Amber turns him into a mouse too. You see, Amber has magical abilities, and it so happens that Ben is a familiar—a creature that stores magical energy. Together they each form half of a powerful wizard. Alone, they're just vermin. Soon Ben and Amber find themselves pitted in an epic battle against a magical enemy who is as crazed as he is evil—and the fate of the world will rest on them learning to work together.