The Exposed (Animorphs #27)

The Animorphs' only true allies, the sentient androids called the Chee, find themselves in serious danger, prompting the kids to come to their aid. As they investigate, they uncover a mysterious and dangerous secret deep beneath the ocean's surface—a secret that could have dire consequences if discovered by their enemies. With the stakes higher than ever, the group faces new challenges in protecting their allies and safeguarding vital information.