The Departure (Animorphs #19)

Cassie's had it. After the last mission, she realizes she's getting tired of missions. Tired of battles. Tired of being an Animorph. She decides that she just can't do it anymore. So she quits.

But the war for her planet isn't so easy to quit. It seems a human-Controller named Karen followed Cassie after the last run-in with the Yeerks, and she knows Cassie has the ability to morph. If she exposes Cassie, it's all over. No more Cassie. No more Animorphs. No more planet Earth.

K.A. APPLEGATE is the author of the bestselling Animorphs series, as well as the Remnants and Everworld series, Home of the Brave, and the Roscoe Riley Rules series. She lives in Tiburon, California.