Katherine A. Applegate

The Earth is being invaded, but no one knows about it. When Jake, Rachel, Tobias, Cassie, and Marco stumble upon a downed alien spaceship and its dying pilot, they're given an incredible power -- they can transform into any animal they touch.

Rachel is still reeling from the news that the Earth is secretly under attack by parasitic aliens known as the Yeerks. And that she and her friends are the planet's only defense....

The Animorphs have one true ally in their battle against the Yeerks: the sentient androids known as the Chee. So when they discover that the Chee—including their friend Erek—are in trouble, they have no choice but to help.

The Yeerks have decided to try a little experiment. They've decided that if they can develop a way to make people more "willing" to be infested, they can speed up Earth's invasion. So the Yeerks try to invent a substance that will take away the human ability to make a decision.

Almost nothing could be as bad as finding out your mother is Visser One, the most powerful leader of the Yeerk invasion of Earth. But it happened to Marco. He knew there'd come a time when he'd have to face her again, knowing that the Yeerk in her brain has taken his mother away....

It was bad when Jake found out his brother was one of them. A Human-Controller. A slave. But that was nothing compared to this. When the Animorphs decide to visit the Yeerks' new base, it seems simple....

Ax is an Andalite, an alien, stranded on a strange planet he's sworn to defend, even though it's not his own. Since the Animorphs rescued him, he's fought at their side, and in that time they've come to consider Ax a friend. But deep inside, Ax knows he isn't their friend....

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....

We found out who Visser Four is. And he has found the Time Matrix, the machine Elfangor had hidden in the abandoned construction site. The same place we met him on a night none of us will ever forget. Especially me. Now Visser Four has the Matrix, and he plans to use it to become Visser One....

The Andalites have returned! The main fleet flew off-course in an effort to stop the galaxy's newest threat – the Rakkam Garoo. But a small crew managed to reach Earth. Now it's up to the Animorphs to decide how to treat their new allies. Can the group be trusted?

The pint-sized Helmacrons may have departed Earth, but they haven't finished causing trouble for the Animorphs and Ax. They left behind a damaged ship—containing morph-tracking technology. Now the Yeerks have found the ship, and are launching a full scale Animorphs hunt....

The Animorphs have met the Ellimist. He helped to save the kids when they were about to be eaten by a Taxxon. He helped to free two Hork-Bajir and restored Tobias's morphing ability. But even though the Ellimist has enormous power, he is not all powerful....

Marco never wanted to be an Animorph. He didn't want the ability to change into any animal he touches. And he certainly didn't want to be one of a handful of kids that are the planet's only defense against a secret alien army. His friends know why he feels the way he does....

Two of the free Hork-Bajir living on Earth have brought the Animorphs and Ax a terrifying discovery: Visser Three has tried—unsuccessfully—to create a race of amphibious Hork-Bajir.

There is an Anti-morphing ray out there. It's purpose: to cause a person in morph to revert to his natural form. And the Yeerks have done a very good job in hiding it. Word from the Chee that the Yeerks are ready to test the weapon. Just one problem: They don't have a test subject.

Elfangor-Sirinial-Shamtul is an Andalite war prince--the one who gave the Animorphs the power to morph. "The AndaliteChronicles" is the story of how this warrior-cadet ended up on planet Earth.

Tobias has gotten used to his new life. He's a red-tailed hawk with the mind of a kid. It was difficult when he first became trapped in his morph, but he's started to come to terms with things....

Really big trouble is an understatement these days. The war with the Yeerks is full on -- and it's definitely going to get worse. But Cassie and the other Animorphs have a lot more going on than just trying to stay alive. Now they've got to actively protect their families and the free Hork-Bajir.

Jake has to attend a wedding out of town. No one has been designated to take over as leader of the Animorphs. But when Tobias tells the others that he's found the place where Visser Three currently feeds, there is a unanimous agreement on going after him.

Ax and the Animorphs are about to have a huge problem. It starts when they decide to morph into mosquitoes in order to slip by some unsuspecting Yeerks, and ends with them stuck in Zero-space with no idea how they got there, no way back to Earth...and no oxygen....