The Yeerks are working on a drug that saps humans of their free will but the Animorphs show them that human free will runs deeper than any drug can reach.
- ISBN10 0613168925
- ISBN13 9780613168922
- Publish Date 1 April 1999 (first published 1 January 1999)
- Publish Status Out of Print
- Out of Print 6 April 2021
- Imprint Turtleback Books
- Edition Turtleback School & Library ed.
- Format Hardcover (Library Binding)
- Language English