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 will 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 depend on them learning to work together.