Cassie didn't pay much attention to the dreams. She and her friends have been having nightmares ever since they acquired the power to morph. But when Cassie discovers that Tobias has been having the exact same dreams about the ocean, and a voice that's calling to them for help, she decides it's time to start listening.

The last time Rachel and her friends entered the giant Yeerk pool beneath their town things went very bad. This time they plan to be careful, and sneak in as roaches, just to spy. Once they're inside, though, the team gets caught. But right as things are looking their most dire, everything stops. Everything. Then Rachel and the Animorphs hear a voice. It belongs to a very old, very powerful being, and it says it can save them. But if it does, the...

Cassie, one of a group of young people who has been given the power to transform into an animal in order to help fight an invasion of the alien Yeerks, decides she is tired of the battle, but she realizes she cannot quit just yet when a human-Controller named Karen learns her secret.

David, the newest Animorph, is not what he appears. His need to control the other Animorphs is all he thinks about. And the things he does are starting to break up the group. Rachel and the others know that time is running out. The newest battle against the Yeerks is the most important one yet. And it's not one that will wait. Winning this fight could mean slowing down the invasion. But no one knows what to do with David. Because the newest Animorph...

RL 5 ; 009-012. Rachael's got some pretty strange stuff happening. She can't control her morphing. What's going on? No one's sure, but Rachael and the Animorphs have to figure it out-quickly.

On trial for treason, Edriss 562 explains how she infested a series of human hosts in order to spearhead the invasion of Earth by her people, the ruthless, parasitic Yeerks.

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.

Jake, Rachel, Cassie, Tobias, and Marco share an adventure in which their unusual abilities to transform into animals help them to solve a strange otherworldly mystery.

Cassie, one of a group of kids who have been given the power to transform into animals in order to fight an invasion of the alien Yeerks, leads her friends into yet another mission when she discovers the Yeerks are trying to access Zone 91, the most secret place on Earth.

The pint-sized Helmacrons left some morph-tracking technology behind, and the Yeerks have found it. As if avoiding a full-scale Animorphs hunt isn't enough, Cassie and the others must keep the morphing cube moving - so it doesn't land in the wrong hands.