The Invasion

The first book in the Animorphs series is narrated by Jake, a teenager who cannot reveal his last name or location because of the Controllers, human beings enslaved by parasitic aliens. He writes his account so that others will learn the truth, hoping humanity can survive until a species called the Andalites returns to rescue Earth.

Jake's life changes on a Friday night at the mall. He is hanging out with his best friend, Marco, after failing to make the basketball team, a team on which his older brother Tom is a legend. Jake had hoped making the team would help him reconnect with Tom, from whom he has been growing distant. On their way home, they run into Tobias, a lonely new kid Jake once defended from bullies, and then encounter Jake's confident cousin Rachel and her quieter, nature-loving friend Cassie, on whom Jake has a crush. The five cut through an abandoned construction site.

Tobias spots a brilliant light descending from the sky, which reveals itself as a small spacecraft with a scorpion-like tail. An alien emerges: a creature with a blue-skinned humanoid upper body, a four-legged deer-like lower body, no mouth, four eyes (two on movable stalks), and a powerful bladed tail. The alien collapses, revealing a fatal burn wound.

The dying alien, an Andalite named Prince Elfangor-Sirinial-Shamtul, warns the children that the Yeerks, parasitic slugs that enter a host's brain and take complete control, have infiltrated Earth. He offers them the power to morph into any animal whose DNA they acquire through touch, using a small blue box from his ship. He warns of a critical limitation: Remaining in any animal form for more than two hours traps them permanently. At the last moment, he privately transfers additional knowledge into Tobias's mind.

With small Yeerk spacecraft called Bug fighters closing in, the children hide as Yeerk forces land. From a larger vessel called a Blade ship emerge Hork-Bajir-Controllers, tall blade-covered creatures enslaved by the Yeerks, and Taxxon-Controllers, massive centipede-like beings. Visser Three, the Yeerk commander on Earth and the only Yeerk to have taken an Andalite host body, taunts the dying Elfangor. Despite his wound, Elfangor strikes at Visser Three with his tail blade. Visser Three then morphs into a massive tentacled monster, seizes Elfangor, and devours him alive. The Andalite's final mental cry of despair echoes permanently in the children's minds.

The group flees. Jake ducks into a half-finished building and narrowly evades a Hork-Bajir and a human voice he finds eerily familiar. All five make it home alive.

The next morning, Tobias demonstrates the morphing power by transforming into his pet cat. Jake reluctantly morphs his dog Homer and is overwhelmed by canine instincts. When Tom enters the room, Jake detects a strange, unsettling smell on him and connects it to the familiar voice from the construction site.

The group meets at Cassie's family farm, where her father runs a Wildlife Rehabilitation Clinic. Rachel shows Jake a newspaper article dismissing the construction site disturbance as teenagers with fireworks, a cover story the group recognizes as planted by Controllers. A policeman arrives asking questions and mentions knowing Tom from The Sharing, an organization Tom has joined, further linking The Sharing to the Controllers. The group debates what to do: Marco argues they should forget everything, citing his responsibility to his father, who fell apart after Marco's mother drowned two years ago, her body never found; Tobias insists they must fight; Rachel agrees; Cassie suggests taking more time.

Later, Marco tells Jake bluntly that Tom is a Controller. Jake punches him in fury, but Marco pins him and reasons with him. Tobias arrives in the form of a red-tailed hawk and shares knowledge Elfangor transferred to him: Every three days, each Yeerk must leave its host and soak in a Yeerk pool to absorb Kandrona rays, an energy produced by a device that simulates their home sun, or the Yeerk dies.

The group attends a Sharing meeting on the beach to gather intelligence. It appears to be an innocent bonfire gathering, but Jake catches a fleeting twitch in Tom's face, a split-second of terrified human awareness before the Yeerk reasserts control. When the full members depart for a private meeting, Jake morphs into Homer to spy. He discovers that Assistant Principal Chapman is a high-ranking Controller. Tom's Yeerk suggests Jake may have been at the construction site and says he brought Jake to the meeting to "either make him ours . . . or kill him" (105). Devastated, Jake maintains his cover and reports back.

Jake resolves to fight, driven by his need to save Tom. Rachel proposes they acquire powerful morphs at The Gardens, a local combined amusement park and zoo where Cassie's mother works as a veterinarian. Marco acquires a gorilla's DNA, Rachel an elephant, and Jake, after accidentally entering the tiger habitat while fleeing security, acquires a Siberian tiger.

Jake morphs a green anole lizard at school to spy on Chapman and follows him to the janitor's closet, where Chapman opens a hidden door revealing stairs descending into a purple-lit pit. From far below, Jake hears a human scream. The Yeerk pool is directly beneath their school.

The group launches their assault that evening. Jake learns Cassie has been captured by a Controller policeman and dragged into the pool entrance. They descend into a vast underground cavern containing the Yeerk pool, a hundred-foot-wide lake of gray sludge. Around the pool, hosts kneel so Yeerks can crawl from their ears, and freed humans scream for help before being caged. At another pier, hosts are forced into the sludge for reinfestation. Tobias reports that Cassie is near the infestation pier and Tom is in a cage, fighting and yelling, confirming he is not a voluntary host.

When they are spotted, the group morphs and attacks. Rachel charges as an elephant, Jake roars as a tiger, and Marco smashes through opposition as a gorilla. Marco rips open Tom's cage, freeing him and other captives. Tobias dives from the ceiling to free Cassie, who morphs into a horse so freed humans can ride toward the stairs. Visser Three appears and morphs into a monstrous creature that hurls fireballs, addressing them as Andalite warriors, not realizing they are human children. Tom charges the Visser and is struck down. Jake leaps onto Visser Three and sinks his tiger jaws into one of the monster's necks, buying time for the group to escape up a narrowing staircase.

They escape with only one freed human. Tom returns home that night, re-infested. Jake lies in bed shaking and crying, knowing his brother never learned the tiger was Jake.

In the early morning, Tobias arrives at Jake's window in hawk form and reveals he cannot morph back: He stayed in hawk form longer than two hours during the battle and is now permanently trapped. Jake is grief-stricken, but Tobias accepts his fate quietly. Jake looks up at the stars and thinks of the Andalite home world. Tobias says the Andalites will come, and Jake wipes away his tears: "Until then, we fight" (185).