Animorphs

Cassie believes her strange dreams are just a side effect of having been given the alien power to morph into an animal, but when she learns that Tobias has been having the same dreams about the ocean, they realize someone is issuing a call for help.

Tobias has stayed in his morph too long and must now live out the rest of his life as a hawk, but that does not keep him from contacting his friends and continuing the fight against the Yeerks, a race of hostile aliens that are invading and controlling the brains of humans.

One day Jake wakes up and finds that he is 25 years old. He tries to find Ax and the other Animorphs to see if they are still opposing the Yeerks, who now rule the earth.

Ax and the Animorphs try to rescue Tobias from the Yeerks.

Marco becomes infested with small aliens called Helmacrons.

Ax and the Animorphs struggle to protect their cube from the Yeerks.

Ax must decide whether to join the Andalites or remain with the Animorphs.

Ax and the Animorphs discover that there are other Andalites like Ax on earth.

The Animorphs try to decide if they should increase their numbers in order to cope with the increasing demands of the war against the Yeerks.