Applegate Katherine Alice. The Animorphs 29. The Sickness

The book is known to have been ghostwritten by Melinda Metz.Cassie and Jake are dragged along by Rachel and the others to the school dance. They have a few good laughs when Ax's unfamiliarity with human culture scares away some of the crowd. The laughter stops, however, when he demorphs involuntarily. It soon becomes apparent that Ax is suffering from an inflamed Tria gland (as well as a fever) - much like the lymphatic tonsils in the human mouth. Unlike humans, though, this gland is located at the back of Ax's brain. If it bursts, it will cause irreversible and fatal damage to the brain. Cassie hides the sick alien in her barn, and Erek the Chee erects a hologram around them both.At the same time, Mr. Tidwell, one of Cassie's teachers, informs her that Aftran has been captured by Visser Three. She will be tortured, and will thus be forced to divulge all of her secrets; including that of Cassie and the Animorphs. Cassie endures her friends' thinly-veiled blame, but they decide to act. They form a plan to enter the Yeerk pool via the facility's extensive piping system. Tobias brings them eels to morph. The children morph and enter the pipes, but Jake falls ill from Ax's virus (Although it is established that this virus will just make humans sick rather than having the fatal effects that the Andalite version has on Ax). The plan fails, and they return to the surface - through a fire hose and into a burning building!That night, Cassie has a bad dream. In the morning, she discovers that Rachel is ill. Mr. Tidwell reveals he shares control of his body with Illim, a Yeerk, and that he is a member of the Yeerk Peace Movement. He tells her the time and location of Aftran's interrogation. Marco is the next to fall ill. Then, while Cassie is with him, Tobias, too, falls ill to it, flying into one of the barn rafters. To keep Tobias safe, she locks him up next to a golden eagle, much to his dismay.Cassie is all alone, and she needs to infiltrate the Yeerk pool, so Illim allows her to acquire his Yeerk DNA and take control of Mr. Tidwell. Cassie and Mr. Tidwell enter the enemy stronghold, and she is disgorged into the Yeerk pool. She finds Aftran's cage, and manages to take control of a voluntary host. She rams the Visser, who drops Aftran. Cassie leaves the little girl, dives back into the pool, morphs her osprey, and carries Aftran away, pursued by Visser Three, who has morphed an eyeball with tentacles.Animorphs is an English language science fiction series of young adult books written by K. A. Applegate and published by Scholastic. It is told in first person, with all 6 main characters taking turns narrating the books through their own perspectives. Horror, war, dehumanization, sanity, morality, innocence, leadership, freedom, and growing up are the core motifs of the series.The story revolves around five humans, Jake, Marco, Cassie, Rachel, and Tobias, and one alien, Aximili-Esgarrouth-Isthill (nicknamed Ax), who obtain the ability to morph into any animal they touch. Naming themselves "Animorphs" (a portmanteau of "animal morphers") they use their ability to battle a secret alien infiltration of Earth by a race called the Yeerks. The Yeerks are a parasitic race of aliens resembling large slugs that take humans as a host by entering and merging with their brain through the ear canal. The Animorphs fight as a guerilla force against the Yeerks, led by Visser Three, and their program to take over the human race. Morphing into animals allows them to battle the various armies of aliens that the Yeerks use, but it also protects their identities. As far as the Yeerks know, only Andalites like Ax have the ability to morph, and if they knew that the Animorphs were mostly human they would be able to easily find out who they are. Protecting their identities becomes more and more difficult as the series goes on because though someone with the ability to morph can change into any animal that they touch, they can only stay in a morph for two hours or they will permanently become that animal. Throughout the series, we see how the war affects the characters in different ways, mentally and physically.