Marco, one of a group of young people who have been given the power to morph into animals in order to aid in the battle against the alien Yeerks, faces an almost impossible challenge when he is called upon to investigate an underwater project which is being overseen by Visser One--an alien ruler that has taken over his mother's body.
Tobias and his friends, a group of young people who have given the power to morph into animals in order to aid the alien Andalites in their battle against the evil Yeerks, face a life-and-death situation when Visser Four, a leader in the Yeerk invasion, finds a time machine.
When Jake's father wants the family to travel to another state, Jake's brother Tom panicks because he can't be away from the Yeerk pool for that long, and when he devises a plan to get his father out of the way, it is up to Jake, and the other Animorphs are forced to choose between saving Jake's father or destroying Tom.
David, Christopher, April, and Jalil, trapped in the surreal Everworld, are ordered by the gods to help battle Ka Anor, and they discover the lost city of Atlantis in the process.
The Animorphs, a group of young people who have been given the power to change into animals in order to fight an invasion by the alien Yeerks, find themselves traveling back in time as they investigate the crash of a Yeerk Bug fighter.
Aldrea, a young member of the outpost the Andalite race has placed on the planet of the Hork-Bajir, must help her native friend Dak when the ruthless, parasitic Yeerks try to enslave his people.
The Animorphs, a group of young people who have been given the power to change into animal form in order to help fight the evil alien Yeerks, find themselves in trouble when Yeerk leader Visser Three discovers a way to cause a person to demorph.
