The blue box Elfangor used to create the Animorphs has been found by David, but David doesn't know what it is. The Animorphs have to get that box at any cost. David ends up on the run with the Animorphs and Ax, and may become the sixth Animorph.
Ax and the Animorphs have a huge problem when they decide to morph mosquitos to slip by some Yeerks. They end up stuck in Zero-space with no idea how they got there, no way to get back to Earth ... and no oxygen.
Rachel, one of a group of young people who have been given the power to change into an animal in order to fight an invasion by the alien Yeerks, worries that her secret power will be revealed when she loses control of her morphing abilities.
As the Remnants struggle to live on a barren Earth, Yago takes off in their spaceship, leaving them stranded, unaware that Tate is aboard ship as well.
The Remnants, a group of people who escaped Earth shortly before an asteroid strike and lived in a suspended sleep state for five hundred years, return to their home planet to find a small population of humans living underground.
