When the Animorphs learn of a Yeerks plan to infest the governor at a hospital while in for minor surgery, they know they have to stop it - expecially since said governor is planning to run for President of the United States pretty soon. Unfartunalety, while saving the governar, Jake falls into a portable Yeerk pool and becomes infested. Now he's one of them. A Controller. And all Jake can do is hope his friends discover what's happened - or else it's game over for Animorphs. And Earth.