Cassie's had it. After the last mission, she realizes she's getting tired of missions. Tired of battles. Tired of being an Animorph. She decides that she just can't do it anymore. So she quits.
But that's not the worst that's happened. It seems a human-Controller named Karen followed Cassie after the last run-in with the Yeerks. And she knows Cassie is an Andalite...or human. Either way, if she exposes Cassie, it's all over. No more Cassie. No more Animorphs. No more planet Earth ...
The Animorphs attack Hork-Bajir bodyguards at a Sharing meeting. The very second Jake orders his team to break off, Cassie tears the throat out of a Hork-Bajir. Cassie, ridden with guilt, runs away. She senses someone watching her, but doesn't pay much attention. She demorphs, and has a nightmare (a scene from Megamorphs #2). She wakes up, and begins scrubbing her teeth and gums until they bleed. The next day, Cassie meets the others at her barn. She explicitly declares that she's fed up with all the violence, and quits being an Animorph. The others are disgusted with her scrupulous behaviour, and brand her a hypocrite. Marco makes a sarcastic remark about Cassie "going back to playing with her animals". Cassie then tells them that her father lost the much-needed funding to keep the Wildlife Rehabilitation Clinic open. A distraught Cassie goes on a horse ride to calm her nerves.
Cassie suddenly spots a girl with red-hair being chased by an angry bear. Cassie pursues them, but is knocked off her horse, and falls into the icy river. When she wakes up, she realizes she'd been saved by the girl. She introduces herself as Karen. Karen tries to force Cassie to reveal her true identity. Cassie laughs and pretends the girl is mistaken. Soon it is apparent that the girl is a Controller, who's Yeerk is called Aftran 942, watching her own father, the president of UniBank. It also becomes apparent that Cassie had killed Aftran 942's brother. They're both lost in the forest, and Cassie knows that a leopard that escaped from a private zoo is lurking about. During their time together, Cassie reveals her identity when she fends off an attack by the leopard.
Cassie begins to discuss the morality of enslaving another creature, while Aftran defends the Yeerk's right to experience life as a human or an Andalite does. Cassie tries to turn Aftran against her own people. Aftran tells Cassie that to preserve the freedom of one species, she must surrender her own. Karen presents Cassie with the following scenario: if she were Karen, would she stay in the Yeerk Pool forever? Cassie is uncertain. She allows Aftran to enter her brain, thus freeing Karen - and putting the life of the planet at stake. Cassie convinces Afran that what the Yeerks are doing is wrong. In return, however, Aftran compels Cassie to morph to a caterpillar, and to live life as a helpless worm. Cassie reluctantly agrees, and morphs, staying beyond the two-hour limit.
Jake and the others soon find Aftran back in Karen's body, and Cassie now a caterpillar. The Animorphs are enraged, and are more than willing to kill the Controller in revenge for Cassie, and to keep their identities a secret. Jake hears her out, though, and lets her live. Cassie spins a cocoon, and stays dormant for a couple of days. Cassie emerges as a butterfly, and the Animorphs are overjoyed, but saddened, as well, certain that Cassie would spend the rest of her brief life as an insect. Ax is puzzled, explaining that Cassie's process is a natural form of metamorphosis, and that she is able to morph back to her old self. Cassie does so, and is willing to be an Animorph once more. Aftran keeps her promise, freeing Karen, and the Yeerk establishes the Yeerk Peace Movement; Karen compels her father to fund Cassie's father's Wildlife Clinic.
|Morpher||Morphs acquired||Morphs used|
- Although the front cover depicts her doing so, Cassie never actually morphs into the butterfly; she morphs into a caterpillar, which metamorphoses into a butterfly, and then demorphs back to human.
- It is not stated whether Cassie can morph into the caterpillar or the butterfly again
- The front cover quote is, "There's always room for a little change...."
- The inside front cover quote is, "Float like a butterfly...."
- This is the third book in which the narrator is the only person to acquire a new morph.
- This book marks the first in the regular series in which more than one Animorph narrates. Jake narrates for part of the story, near the end, due to Cassie being trapped as a caterpillar in a chrysalis.