Katherine Stone hates her brother Jeff. She wishes she could turn into a dog and bite him. She knows it can be done. She's sure that the big gray wolfhound her friend Mark sometimes walks is really his Nana. If she could only figure out how Nana does it. It has something to do with that purple stone in her collar.

"Be careful what you wish for," Katherine's mom would say.

On her way home from school, a big man with green hair stalks her and snatches her cell phone. Before he can get away, the wolfhound, also known as Mark's Nana, attacks the bully and takes something from him.

Katherine follows the dog home, where a chain of events leads her to a strange purple light that seems to invite her to look into it. She does, and things get weird.

She is swept into an adventure to save an alien world called Estalan, where the people are shape shifters who can change into animals. Estalan has suffered an ecological disaster, leaving it vulnerable to some powerful enemies that will stop at nothing to reach the planet and destroy its inhabitants. For a long time it has been a protector of Earth. Now it needs the help of its friends--including Katherine.

Recommended for ages 8-12.