- Narrator: Marco
Marco's father is nearly captured and infested, and Marco reveals himself in the process of rescuing him.
Tropes:
- Adults Are Useless: The Animorphs have always felt this way, but it's the first time one of their uninfested parents is hit with the reality that their children don't trust the authorities, or them to make good decisions.
- Big Damn Heroes: Marco in gorilla morph takes down two of the Hork-Bajir Controllers who captured his father, only to be taken down by the next two. Then Rachel in grizzly bear morph crashes the party, and there are no more Hork-Bajir Controllers left to be a problem.
- Big Damn Reunion: After much hardship, tears, and lies, Marco finally reunites his parents at the end of this book.
- Break His Heart to Save Him: In one of the most cold-blooded moves he's made, Marco sacrifices Nora to the Yeerks and then blatantly lies to his dad by implying she was a Controller all along in order for Peter to not ask about her again now that he and Eva are reunited.
- Elite Mook: The Blue Band Squadron are jacked up Hork-Bajir Controllers who answer personally to Visser Three. One of them is enough to tear apart Rachel in Hork-Bajir morph.
- Enemy Civil War: Marco exploits the confusion in the Yeerk pool to make two squadrons of Hork-Bajir Controllers fight each other.
- Faking the Dead: With Erek and Mr. King's help, Marco fakes himself and his father being vaporized by cop-Controllers.
- He Knows Too Much: Peter proves to be smart enough to understand stolen Andalite technology, so the Yeerks move to infest him as soon as possible.
- Humans Advance Swiftly: Ax is both impressed and miffed that humans manages to build a Z-space transmitter in less time than it took the Andalites to do the same.
- Lured into a Trap:
- Peter is given a call saying that a co-worker died and his wife needs to be consoled, and Peter is the only one who knows what it's like to lose a spouse. The dead guy is actually alive and a Controller, and the call was part of a setup to get Peter infested.
- Marco pretends to be a tourist having seen an alien in the woods (Tobias in Hork-Bajir morph) so that the Yeerks will send a Bug fighter to capture the freed Hork-Bajir and silence the human who saw it. The Animorphs capture the two Hork-Bajir Controllers and leave them for Toby to find, and kill the Taxxon-Controller pilot to man the Bug fighter back to the Yeerk pool's hangar.
- Public Execution: Visser One is sentenced to a public Kandrona starvation. Eva's body is tied up on the infestation pier where everyone in the Yeerk pool can see her, and Edriss is not allowed to leave or be killed on the spot, even with all the life-saving Kandrona all around her.
- Sacrificial Lion: Nora. She and Peter love each other, and she loves Marco like a son, which is unfortunately one-sided because she's in the way of Marco's family reunion. Marco doesn't bother trying to save her when the Yeerks come calling, then manipulates his father into thinking she never loved him, completing his character arc and becoming The Unfettered.
- Squashed Flat: The final fate of Edriss 562, AKA Visser One, is to be stomped on by Marco's gorilla foot while she's inches from the Yeerk pool.
- Wham Episode: Marco reveals himself and the Animorphs' mission to his dad. Visser One dies, and Eva is freed. Marco's family has to be exiled to the free Hork-Bajir valley to avoid the Yeerks. The Animorphs have access to a Z-space communicator, at the end of the book using it to contact the Andalite fleet.
- You Have Failed Me: Visser One failed her mission in the Anati system, and so the Council of Thirteen decided to execute her on Earth.
