When Jake has to leave town for a family thing, the other Animorphs and Ax figure life will pretty much be normal until he gets back. But when Tobias discovers Visser Three's newest feeding place, the kids decide they have to check it out.

But there's no assigned leader. Now Rachel, Tobias, Cassie, Marco, and Ax have another problem: Who will be the best one for the job? Because being in charge isn't just guts and glory. It's about making decisions that will mean the difference between life . . . and death.

Visser Three is still trying to find a way to reach the Pemalite ship. The ship that was hidden thousands of feet below the ocean's surface. A ship containing technology so advanced that it is 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, the other Animorphs, and Ax acquire additional deep-sea morphs in order to stop the visser's plan. But while trying to destroy the Yeerk ship, the kids make a startling discovery: an underwater civilization. Have the kids discovered Atlantis . . . or is it just another trap?

In an hour or so, once I was out of sight of land, I would lower my sails and wait for a Bug fighter to come lift me off the deck. The engine backwash of the Bug fighter would capsize the boat. Or I might put the Taxxon pilot to the test and see if he could ram the low-slung boat. That would puzzle the humans.Either way, my body would never be found...My time of lying low was over...I would spearhead the invasion of Earth. I would take charge of our greatest conquest. I would stand alone atop the Yeerk military hierarchy.I was to become Visser One.From the Hardcover edition

Marco already knows he has a few problems: the constant battle with the Yeerks; finding out his mother was infested . . . and is now Visser One. The leader of the Yeerk invasion of Earth. But things are about to get even weirder. Marco's father is thinking of getting married again.

Meanwhile, the Animorphs and Ax have other things to worry about. It seems the Yeerks are trying harder than ever to get people into The Sharing. Now the kids have to find a way to slow down recruitment. But Marco's personal stress is causing him to morph into creatures that don't exist. Creatures the Yeerks are sure to notice . . . and attack. . . .

There is a chance for the free Hork-Bajir on Earth to help start a rebellion against the Yeerks on the Hork-Bajir homeworld. And they've learned from the last surviving Arn—the race that created the Hork-Bajir—that Aldrea, daughter of Prince Seerow, knew the location of a stolen Yeerk vessel packed with weapons.

Unfortunately, the only way to recover the ship is to ask Aldrea herself—and she's dead. But the Arn has Aldrea's persona stored. And Cassie, Rachel, or Toby Hamee are the closest match. The only problem is that once Aldrea gets into one of their minds, she may not want to come out. . . .

Tobias, the other Animorphs, and Ax already have a few problems: saving the world, keeping their identities secret, finishing their homework. Now they have one more thing to add to the list. The Yeerks have discovered a way to cause a person to demorph. And with this new device Visser Three plans on capturing "the Andalite bandits."

Now what? The Animorphs and Ax realize they have to get rid of the device—or be captured by the Yeerks. And the risk of getting caught is very high. That's when Tobias comes up with the only possible plan. Someone has to acquire Ax. . . .

Rachel is falling apart. Literally. Her newest morph has the ability to regenerate its limbs, but when Rachel demorphs there's a lot more Rachel than when she started out. One more Rachel, to be exact. Rachel is an okay person to have around. But two could be considered overkill. Especially two Rachels with completely opposite personalities: one is pathetically weak; one is super strong and super nasty.

Now the Animorphs have to figure out a way to put Rachel back together again. Because if it's up to the "twins," Rachel the weak will surrender to Visser Three. Rachel the super bold will try to single-handedly take him down. And twice the trouble may be twice as much as the other Animorphs and Ax can handle. . . .

Jake's great-grandfather has died. It blows the family away—especially Jake's mom. So Jake's parents decide they should all travel to the great-grandfather's home to help with any arrangements. In another state. For three or four days.

This is a very big problem for Jake's brother, Tom. He can't be away from the Yeerk pool for that long. So Tom refuses to go—and his father insists. But Tom's Yeerk will do anything to survive. Including making his father less of a problem.

Now Jake, the other Animorphs, and Ax have to find a way to protect his father without Tom discovering their secret. And without having to choose between his father's life. . . and Tom's.

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, the other Animorphs, and Ax 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 away the secret of the Animorphs. . . .

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.But Jake, Rachel, Cassie, Marco, Ax and I can't let that happen. We can't let him alter time so that the Yeerks will win the invasion. So we're prepared to make the ultimate sacrifice. Eventually, one of us will lose this fight...

Something is very wrong with Ax. He's sick. And the Animorphs don't know what to do about it. They can't take him to a hospital. They don't know how to contact the Andalite home world. And Ax is dying.

Cassie and the other Animorphs come up with a plan. But it involves finding a new way into the Yeerk pool. There's just one problem: Jake, Rachel, Tobias, and Marco come down with Ax's sickness. And now, for the first time, Cassie is on her own. . . .

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 and Ax are not only faced with trying to slow down the Yeerks' invasion, but they also have to put an end to the genetic testing on a small group of humans. This time there's only one chance to stop the Yeerks. And if anything goes wrong, it's all over. . . .

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

But the Chee's problem is much deeper than anything the kids could have imagined. It's hidden in the ocean. So far down that no human has ever traveled there—and survived. And the Animorphs realize what will happen if Visser Three discovers the valuable secrets of the Chee. One of which is the Animorphs. . . .

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. He has an enemy. The Crayak.

So, the Crayak and the Ellimist decide that a battle will prove their ultimate power. But they don't intend to fight each other. The Ellimist will choose the Animorphs, Ax, and Erek, the Chee; the Crayak will choose his own army. If the Animorphs lose they will be erased from the universe altogether. And there'll be no one left to fight the Yeerks. . . .

It's time for the Animorphs to acquire some cold-weather morphs. The Yeerks are at it again, and they're causing trouble near one of the coldest places on earth: The North Pole.

Cassie, the other Animorphs, and Ax have a few little problems. A few very little problems. Actually, the problems call themselves Helmacrons. They're less than an inch tall, and they're pretty upset at Cassie. They believe she stole their ship. Cassie thought it was just a toy, and gave it to charity. Now the Helmacrons want it back.

So the Animorphs and Ax have a new dilemma. Because the Helmacrons have their own secret weapon: They can shrink other beings down to their size. And, if they don't get their ship back soon, everyone on the planet is in for a little surprise...

Someone's looking for Tobias. Someone who says she's his long-lost cousin. Tobias isn't sure the person is telling the truth. But she's really nice, and knows a lot about him. And what she tells Tobias definitely gets his attention.

It seems a lawyer has discovered Tobias's father's last will and testament. So, Tobias needs to attend the reading. His "cousin" even offers to go along. But something just doesn't feel quite right. That's when Tobias, the other Animorphs, and Ax decide to do a little checking on this "cousin". And what they discover will change the rest of Tobias's life....

Chronicling the lives and fortunes of Dak, a Hork-Bajir Seer, born to save his people from a Yeerk invasion and Aldrea, a female Andalite, sent to the Hork-Bajir planet after her father's misguided kindness gave the Yeerks their power.

David, the newest Animorph, is not what he appears. His need to control the other Animorphs and Ax 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 is more than just a little problem. He's deadly. . . .

There is a new Animorph. And he's arrived just in time, because the Yeerks are preparing their biggest takeover ever. The ultimate target: the world's most powerful leaders gathered together in one place. What better way to get into the minds of humans? Literally.

At first, David joins the fight with a vengeance. But there is definitely something wrong. Because he's starting to break the rules. Taking risks that could get them all captured. Or killed. The Animorphs don't know what to do. Because there was a time when the Yeerks were their greatest enemy. That's about to change. . . .