Applegate Katherine Alice. The Animorphs 52. The Sacrifice

The book is known to have been ghostwritten by Kim Morris.During a reconnaissance flight taken by Rachel, Ax, and James, the Animorphs learn that the Yeerks are herding people into the subway system. The subways have been redirected to the Yeerk pool complex, where humans are being infested en masse.Back at the Hork-Bajir valley, Rachel makes her report to Jake. Marco comes up with a plan to use the subway system to destroy the Yeerk pool by loading one of the pool-bound trains with explosives and detonating once the train reaches its destination. Despite some resistance from Cassie, the Animorphs agree to carry out the plan.Later that night, Ax sneaks away from the camp with the zero-space transmitter constructed by Marco's father. Ax contacts the Andalite military and tells them of the Animorphs' plan to destroy the Yeerk pool. The Andalites do not support the plan and feel that the war for Earth is lost. Ax is ordered to sabotage to Animorphs' operation to destroy the Yeerk pool so that the Yeerks will continue concentrating the majority of their forces on Earth, allowing the Andalites to wipe them out more easily.The next morning, the Animorphs finalize their plan to destroy the Yeerk pool. During the meeting, Cassie breaks down and confesses that it was she who allowed Tom to escape with the morphing cube. Despite this realization, the other Animorphs forgive Cassie for her actions and continue planning the operation, with the exception of Ax, who feels a cold hatred towards Cassie for letting Tom take the cube.After the meeting, Ax pulls Cassie aside and asks her to justify her actions. She recalls Aftran 942 and the Yeerk Peace Movement, and speculates that the morphing technology could give the Yeerks a means to abandon their policy of infesting sentient beings and instead morph new bodies. Ax concedes that he encountered a Yeerk who planned to do this on the subway mission, though he also speculates that the Yeerk could have been lying. After speaking with Cassie, Ax talks with Tobias, who voices his support of Cassie's reasoning. Ax decides to disobey his orders and not sabotage the plan to destroy the Yeerk pool.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.