Marco is determined to save his father from the Yeerks.

Cassie's had it. After the last mission, she realizes she's getting tired of missions. Tired of battles. Tired of being an Animorph. She decides that she just can't do it anymore. So she quits.But the war for her planet isn't so easy to quit. It seems a human-Controller named Karen followed Cassie after the last run-in with the Yeerks, and she knows Cassie has the ability to morph. If she exposes Cassie, it's all over. No more Cassie. No more Animorphs....

The newest Animorph may prove a greater threat to the team than the Yeerks who are again threatening the world.

When Marco runs into his old friend Erek he doesn't think too much of it. He's got more important things to do, like helping to save the world. But then Marco finds out Erek's been hanging with some of the kids at the Sharing, and he starts to think that something just a little weird is going on.So Marco, Jake, and Ax decide to morph and check old Erek out. Just to see if he's been infested with a Yeerk. The good news is that Erek's not a human-Controller....

"When Doggo and Pupper meet a baby bird who also has worries, they are determined to help. Doggo and Pupper may not know how to fly, but they are very good helpers. Maybe they are even heroes!"

Someone crashlanded a Yeerk Bug fighter , and the Yeerks have been trying to cover it up, but not before Tobias spots it , So the Animorphs and Ax decide to steal the ship to show the world that Earth has been invaded.

The Animorphs have to make the most important decision they've ever faced: Do they continue to fight the Yeerks in secret, or is it time to let everyone know there's a resistance? That the Animorphs exist and Earth does stand a small chance against the invasion. Jake knows that either choice is a major one, not something that a kid should be responsible for. But he's getting tired of the pressure. Even though he realizes his friends need him to...

The war between the Yeerks and the Animorphs is still raging. There are no more secrets - but there are plenty of lies. The kids are fighting harder than they ever thought they could. And they're about to make the biggest decision they've ever had to face. A decision that may eventually break them all. Ax and the Animorphs know that destroying the Yeerk pool would give them a huge chance to take back Earth. And they've figured out a way to do it....

We never should have done it. But we needed a break. Some time off from the superhero stuff. A chance to act like normal kids. Well - as normal as four kids who can morph into animals, a boy trapped in a hawk's body, and a bright blue alien can be. Everything should have been cool. Now Rachel is missing. And there's this... this thing that's after us. But it's not up to me to tell the whole story. Tobias, Cassie, Marco, and Ax were there, too....

The Animorphs have managed to contact the Andalite home world, but the battle is far from over. Visser Two has arrived on Earth, and he's not happy about the state of things. He decides the best way to take over Earth is to have the humans destroy each other, exhausting their weapons in the process. He's going to start World War III. Ax and his friends know that Visser Two means business. There are only two ways to keep him from destroying everything...