Animorphs #2: The Visitor
"If someone told you Earth was under a secret invasion, what would you think? Rachel had a hard time believing it, even after she and her friends saw what they say--and received an incredible power. The power to become any animal they touch.
Rachel knew they were in danger from the start, so when it's suggested they use their new powers to spy on one of their enemies, she rises to the challenge. But when she discovers what they'll have to do to win, will it be more than Rachel can handle?"
ISBN: 0545291526 / 9780545291521
Author: Katherine Applegate
Publisher: Scholastic Inc.