The Decision (novel)

Plot summary

The Animorphs discover that a high-ranking member of the Secret Service, Hewlett Aldershot III, has been intentionally injured by the Yeerks and is being kept secretly in a hospital where he is heavily guarded. Since he cannot be infested while in a coma, Visser Three acquires his DNA in hopes of impersonating him to eventually acquire an even more senior official. They decide to morph mosquitoes with the theory that they can acquire him by sucking his blood without being in their natural forms where the Yeerk guards might notice them.

While in mosquito morph, they are transported to Z-Space when their extra mass is caught in the slipstream of an Andalite ship heading for the planet Leera where there is a Yeerk invasion underway. Just before they suffocate, they are rescued and taken aboard. Once on the ship, Ax begins to ignore the Animorphs, instead following orders from the captain. The humans are told to stay calmly in a room while the Andalites do all the work. Unfortunately, the captain of the ship reveals himself to be a traitor. He incapacitates the other Andalites on the bridge, stunning most and amputating the tail blade of the tactical officer. Ax is held, unharmed, as a hostage. Ax calls out to the Animorphs for help but they reveal to Ax that they are already present in the room. Cassie and Ax distract the captain long enough for the tactical officer to kill him. As the ship is about to be taken by the Yeerks, the tactical officer instructs them to leave while he initiates the self-destruct sequence.

The Animorphs head across the major landmass of Leera to try to find friendly Andalites. Tobias suddenly and mysteriously disappears, but the others don't know where he's gone and are forced to move on without him. Ax is struck with a sudden realization, and the Animorphs follow him out into the ocean. Rachel disappears like Tobias, and the others rescue a group of Leerans from Yeerk control. The Leerans agree to be acquired in order to help fight off the Yeerk invasion. In their new Leeran morphs, the Animorphs enter a Leeran city. The Andalites-based there inform the Animorphs that they have planted a bomb to explode the continent, just as Ax had suspected, but that it needs to be activated. Just as the Animorphs volunteer for the mission, Marco disappears, causing a panic among Ax, Jake, and Cassie. After explaining their problem to the Andalites, the Andalite scientists theorize that the Animorphs' unexplained disappearances are the result of a "snapback" effect, meaning that when the Animorphs disappear, they are reappearing either on Earth or in Z-Space.

Soon after they set out to activate the bomb, they meet a Leeran-Controller who reads their minds and alerts the Yeerks of the bomb. After dealing with the Leeran, Cassie disappears. When they reach the explosives, Jake disappears, leaving Ax alone. He activates the bomb but a platoon of armed Hork-Bajir appear in an attempt to disarm it. A Hork-Bajir fires at him, but he disappears right before the beam hits him. The bomb goes off right after he disappears. All the Animorphs arrive back to the hospital, where they were before they got sucked into Z-Space. Hewlett Aldershot III wakes up, apparently healthy again.

The Animorphs celebrate their victory at the food court, and Ax silently realizes that the Animorphs are the true people that he must follow, especially in the light of the traitorous Andalite captain. Glad to get back to normal with them, he is ready for his favorite snack: cinnamon buns.

Morphs

In chapter 15, in the battle for control of the Ascalin, several of the Animorphs are hidden in fly and cockroach morphs. The book never specifically indicates which of them was what insect, except for Cassie, who was in flea morph.