The book is known to have been ghostwritten by Ellen Geroux.
The Yeerks have finished their anti-morphing ray and want to test it. Tobias comes up with a plan to trick the Yeerks into thinking that it doesn't work; if they capture him, they will try to use it on his hawk form, but hawk is his true form now. Tobias acquires Ax — thus allowing him to 'demorph' and reinforce the impression that he is a genuine Andalite — and then gets captured by the Yeerks. Rachel was supposed to be with him in fly morph to be able to rescue him and tell the rest where the lab was. However, sub-visser Taylor gave them an anesthetic so she couldn't grip to Tobias and fell to the floor. Tobias, alone and trapped, tries to get demorphed unsuccessfully since he is already demorphed. He is then tortured by the sadistic Taylor with a machine that controls the parts of the brain that induce pain and pleasure. He almost goes insane and nearly dies after receiving heightened, alternating doses of painful and pleasant sensations and memories. He sees painful memories of childhood neglect or battle, after seeing pleasant peaceful memories. This process nearly kills him. Here, he experienced an Utzum, later explained by Ax to be a vision ancient Andalites believed happened at the moment of death to comfort those crossing over. (Ax mentions that Andalites no longer believe this.) These images are supposed to be passed through DNA. Tobias is spoken to by his father Elfangor who shares with him his own memories of hardship, battle, his moments of questioning himself and his own actions. He reminds Tobias that he is part of a great tradition of warriors in order to comfort him before his death. Tobias is rescued by Ax and the other animorphs. In the battle he persuades Rachel not to kill Taylor, so as not sink to her level. After the battle Tobias continues to question who and what he is. Andalite? Human? Hawk? However he takes comfort in his relationship with Rachel and they kiss for the first time in the main series.
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.