The Unknown
Popularity 19
Having learned that someone has discovered proof of alien life and hidden the proof on the top-secret base called Zone 91, Cassie and the Animorphs struggle to keep the evil Yeerks away from the place.
Juvenile fictionScience fictionMetamorphosisExtraterrestrial beingsFictionChildren's fictionAnimorphs (fictitious characters), fictionExtraterrestrial beings, fictionseries:AnimorphscollectionID:Animorphs