Book 16

The Warning

by Katherine Applegate

Published 21 May 1999

Book 17

The Underground

by Katherine Applegate

Published 18 June 1999

Book 18

The Decision

by Katherine Applegate

Published 1 May 1998
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. It ends with them stuck in Zero-space with no idea how they got there, no way to get back to Earth...and no oxygen.

Book 19

The Departure

by Katherine Applegate

Published 17 September 1999

Book 20

The Discovery

by Katherine Applegate

Published 15 October 1999
It's not what you expect to see when you're calmly walking down a school corridor. A boy carrying a piece of Andalite morphing technology. Marco and the other Animorphs have to get the Andalite blue box off David - he may have no idea what it is but the Yeerks do. And they'll do anything to get it. Part one of a trilogy.

Book 21

The Threat

by Katherine Applegate

Published 1 September 1998
"The Threat" is a new Animorph named David. At first he's a valuable warrior. But as crucial battle plans unfold, the Animorphs realize they've made a terrible mistake.

Book 22

The Solution

by Katherine Applegate

Published 10 December 1999

Book 23

The Pretender

by Katherine Applegate

Published 21 January 2000

Book 24

The Suspicion

by Katherine Applegate

Published 19 February 2000

Book 25

The Extreme

by Katherine Applegate

Published 17 March 2000

Book 26

The Attack

by Katherine Applegate

Published 1 February 1999
The Ellimist has helped the Animorphs many times. He is all-powerful and has only one enemy, the Crayak. In a cosmic showdown, the two enemies choose champions to represent them in a battle to end all battles. The Crayak chooses the dreaded Howlers. The Ellimist chooses the Animorphs.

Book 27

The Exposed

by Katherine Applegate

Published 19 May 2000

Book 28

The Experiment

by Katherine Applegate

Published 16 June 2000
Ax and the Animorphs are confused - and worried. The Yeerks have taken over an animal-testing and meat-processing plant. Are they trying to poison human food? It doesn't make sense - the Yeerks need their host-bodies alive and healthy. The factory and lab must be connected - what are they testing? And what - or who - are they using for lab-rats...There's only one way to find out what's going on. The Animorphs have to go in. Which means disguise-morphs. Which means that somebody has to morph a cow, and then walk right into a slaughterhouse...

Book 29

The Sickness

by Katherine Applegate

Published 1 May 1999
The Yeerks have captured Aftran - the rebel Yeerk working for peace between humans and the Yeerk invaders. Aftran has been in Cassie's brain. When Visser Three interrogates her, he will find out about the Animorphs, Ax, the Chee - everything. The Animorphs have to rescue Aftran - to save themselves. Except they can't. Some kind of illness is going through the team - Ax is so sick that his only chance is an operation, and the other's can't even walk, let alone fight. Only Cassie is OK. So she's got to break into the Yeerk pool on her own, rescue Aftran, and then come home to do brain surgery...

Book 30

Reunion

by Katherine Applegate

Published 22 May 1998
Marco is faced with a difficult decision when his mother threatens to seize control over Visser One.

Book 31

The Conspiracy

by Katherine Applegate

Published 15 August 1999
While at a meeting of The Sharing, Jake's father is threatened with Yeerk infestation at the hands of his own son, yet when Jake acts on a plan to help his father, his brain suddenly locks up and leaves him helpless at a very crucial time.

Book 32

The Separation

by Katherine Applegate

Published 1 August 1999
When Rachel morphs into a starfish she has the ability to regenerate her limbs, but when she demorphs back to being Rachel there is more to her than when she started out, a twin who is super strong and even nastier than she is.

Book 33

The Illusion

by Katherine Applegate

Published 1 September 1999

Book 34

The Prophecy

by Katherine Applegate

Published 15 November 1999
The resistance force on the Hork-Bajir homeworld has long been wiped out. Now the Hork-Bajir colony on earth could help to start the fight again. But only a dead Andalite knows where to find the weapons cache that they'll need to destroy the Yeerks...But the dead CAN live again. The Andalite's Ixcila - her personality - has been stored. But like a Yeerk, it needs a host body to inhabit. One of the Animorphs has to let her into their head. Who will it be? And will the dead Andalite girl ever want to let her new body go?

Book 35

The Proposal

by Katherine Applegate

Published 31 December 1999
The Yeerk infiltration contiues. Things seem to be going from bad to worse for Marco. His mother - now controlled by the disgraced ex-leader of the Yeerk invasion - has disappeared after their last showdown, but she may still be alive. Of course, Marco's father thinks she's dead, and he's getting scarily close to his new girlfriend, who just happens to be Marco'c maths teacher. With problems like these, it's no wonder Marco's watching TV agony programmes - only to find his favourite presenter recommending The Sharing, the front organization for the Yeerks