Book 36

The Mutation

by Katherine Applegate

Published 1 December 1999
Morphing into killer whales, the Animorphs discover a whole new world where humans with gills exist in the deep waters below.

Book 37

The Weakness

by Katherine Applegate

Published 1 January 2000
When Tobias discovers a new alien feeding place while Jake is away, he and the other Animorphs determine to do something about it, but without a designated leader they find the project more difficult than they expect.

Book 38

The Arrival

by Katherine Applegate

Published 1 February 2000
Four Andalites arrive on Earth to help fight the Yeerks, but they don't want to work with the humans and demand that Ax choose sides.

Book 39

The Hidden

by Katherine Applegate

Published 1 March 2000
The Yeerks plan to use the Helmacron ship they have repaired to capture the Andalites and track down Elfangor's blue cube--the cube that gives Cassie, and the other animorphs the ability to morph.

Book 40

The Other

by Katherine Applegate

Published 1 April 2000
Ax and the Animorphs find new hope when they learn that he is not the only non-infected Andalite on Earth.

Book 41

The Familiar

by Katherine Applegate

Published 1 May 2000

Book 42

The Journey

by Katherine Applegate

Published 15 July 2000
The Helmacrons are back, and this time they're determined to get hold of the morphing cube. Despite their size, they have devised a sure-fire way of getting the Animorph's attention-they're inside Marco, and they're heading for his heart. (Well, there's a few things that being a millimetre and a half tall is good for.) The Animorphs must take them on, but that means shrinking, and a battle...and the battlegrounds is Marco's body. Thing is, Marco's got his own mission-a kid captured him morphing on camera. He's got to find it and destroy the evidence, but as long as the Animorph s are inside him, he can't morph. Can he succeed without his most important weapon?

Book 43

The Test

by Katherine Applegate

Published 15 August 2000
Taylor, Tobias' arch-nemesis and the Yeerk that once infested his mind, holding him, his memories, his every thought and feeling hostage,has kidnapped him once again. Only this time, she's going to let him go-after he's listened to her proposition...Taylor is now part of the Yeerk peace faction and tells the Animorphs of a plan to eliminate the Visser and the Yeerk pool, a plan which only the Animorphs can carry out. This would be a major victory in their war against the Yeerks, but it also means morphing to the creature with the most uncontrollable instincts-the Taxxon. Can Tobias prevent the morph from turning him against his friends...?

Book 44

The Unexpected

by Katherine Applegate

Published 15 September 2000
After the Animorphs' latest mission goes disastrously wrong, Cassie's finds herself alone, on a plane, heading who knows where and with Visser Three hot on her tail.The Yeerks have her trapped, thirty-three-thou feet in the air, with no escape and no Jake, Rachel, Marco, Ax or Tobias to save her. How will she ever defeat the Visser without the help of her friends-and how on earth can she find her way back home.?

Book 45

The Revelation

by Katherine Applegate

Published 15 October 2000

Book 46

The Deception

by Katherine Applegate

Published 15 November 2000
"The animorphs have never met Visser Two. Until now"--Cover.

Book 47

The Resistance

by Katherine Applegate

Published 15 December 2000

Book 48

The Return

by Katherine Applegate

Published 15 January 2001
Rachel is captured by David, the sixth Animorph who was once trapped and left on a deserted island. He's back and wants revenge.

Book 49

The Diversion

by Katherine Applegate

Published 28 February 2001
The Yeerks finally realize that the Andalite Bandits are not aliens, but humans. Now, Tobias and the other Animorphs must protect themselves.

Book 50

The Ultimate

by Katherine Applegate

Published 15 March 2001

Book 51

The Absolute

by Katherine Applegate

Published 28 April 2001
The Absolute: The Yeerks are on to the Animorphs - and now they're in hiding. Things are falling apart, and for once, Jake may not be be able to make the decision that will save them...The Sacrifice: The war between the Yeerks and the Animorphs is still raging. There are no more secrets, but there are plenty of lies. The Animorphs are fighting harder than they ever thought they could. And they're about to face the biggest decision they've ever had to make. A decision that may break them all.

Book 52

The Sacrifice

by Katherine Applegate

Published 28 May 2001
The war between the Yeerks and the Animorphs is still raging. There are no more secrets but plenty of lies. The kids are fighting harder than ever and they are about to make the biggest decision--a decision that may eventually break them all. Ax and the Animorphs have known that the ultimate destruction of the Yeerk pool will give them a huge chance to take back Earth. And they have figured out a way to do it. But there's no way to destroy the pool without destroying everyone else that may be there. And there's no more time to think about it. There's only yes or no.

Book 53

The Answer

by Katherine Applegate

Published May 2001
The Answer: The Animorphs have found a way to slow the Yeerks down, but now the Yeerks have decided the best way to win is to just destroy everything and everyone who gets in their way. The Beginning: No one ever thought it would come to this...The final battle and the extraordinary conclusion to this best-selling series.

Book 54