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 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.

"Jake, Rachel, Tobias, Cassie, and Marco have a feeling they know where the Yeerk's new base is located. And they've even figured out how to get in -- how many people will really notice a few flies on the wall? But they never figured that they might get caught. Or that Jake could fall into the Yeerk pool. That Jake could become a human-Controller..."--Cover.

What would you do if you were the only alien trapped on a strange planet? Probably freak out, right? Well, that's what Ax feels like doing. But as an Andalite warrior-cadet, he has to be pretty cool about stuff like that. He's been hanging out with the Animorphs ever since the Dome ship was destroyed by the Yeerks and his brother, Prince Elfangor, was destroyed by Visser Three. Life on Earth is pretty different for Ax. But there is one thing he,...

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....

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.

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.

Jake finds a Web site devoted to the Yeerks that could be a trap so they must move quickly.

Ax and the Animorphs are about to have a huge problem. It starts when they decide to morph 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.Luckily, an Andalite scout ship finds them before it's too late. But now Ax is finally with his own people. And he doesn't know if he ever wants to go back to Earth. K.A. APPLEGATE is...

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.

David's attempts to control the other Animorphs threatens to break up the group.

Animorph Cassie and Ax have to find a way to to keep the Helmacrons from shrinking other beings down to an inch.

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. A substance that will eliminate free will. Now the Animorphs are not only faced with trying to slow down the Yeerks' invasion, but they also have to put an end to the genetic...

Marco's mom is back. But she's not Visser One anymore. Marco's not even sure if she's still a Controller, but he's determined to find out. No matter what it takes. No matter what might happen. Marco wants his mom back. Jake and the other Animorphs realize that Marco is under some serious stress. And that the situation with his mom could very well jeopardize everything they've worked for. Now they also have to wonder if Marco will be the one to give...

Rachel, one of the Earth teenagers dedicated to stopping the parasitic alien race known as the Yeerks, is horrified when she finds herself split into two nearly identical girls.

The Animorphs assist in helping to start a rebellion against the Yeerks.

Visser Three is still trying to find a way to reach the Pemalite ship that was hidden thousands of feet below the ocean's surface. The ship contains technology so advanced that it's superior to anything even the Andalites have built. And this time, the Visser plans to find the ship so he can use the power to complete Earth's invasion. Jake and the other Animorphs acquire additional deep-sea morphs in order to stop the Visser's plan. But while trying...

The Animorphs and Ax have allies willing to fight against the Yeerk invasion now that Andalites have finally arrived on earth. But there are only four of them and they don't want to fight alongside humans. Ax must choose a side. His friends? His people?

Ax, who has always believed that he is the only non-infested Andalite on Earth, discovers that there are others trying to survive until help finally comes.

Sometimes your worst problems are the ones you can't actually see. Like the Helmacrons. These less-than-an-inch-high aliens are back, and they want the morphing cube more than ever. Obviously Rachel and the other Animorphs can't let them take the cube. But when Rachel tries to stop the Helmacrons from stealing it, Marco gets in the way and ends up with tiny aliens, well, up his nose. Rachel and the others can't let the Helmacrons stay inside Marco's...

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...

David, the traitorous Animorph, is back. When the Animorphs decided to give another human being the power to morph, it was one of their biggest mistakes. David tried to destroy them all - and almost succeeded. Rachel and the others thought they'd seen the last of him when they trapped David as a nothlit, leaving him on a deserted island to live out his days as a rat... They were wrong. Rachel knows what a threat David is. He's cunning and dangerous....

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. And they no longer believe they can do it alone. The Yeerks are just too powerful. So Cassie and the others have to ask themselves a very important question:...

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....

The final battle between the Yeerks and the Animorphs is at hand. No one knows who will win, lose, or live.