What would you do if you were the only alien trapped on a strange planet? Probably freak out, right? Well, that's what Ax feels like doing. But as an Andalite warrior-cadet, he has to be pretty cool about stuff like that. He's been hanging out with the Animorphs ever since the Dome ship was destroyed by the Yeerks and his brother, Prince Elfangor, was destroyed by Visser Three.

Life on Earth is pretty different for Ax. But there is one thing he, Cassie, Marco, Jake, Rachel, and Tobias have in common. Something that one alien, four kids and a hawk know they have to do...stop the Yeerks...