Marco's mother, the host to Visser One, is revealed to have survived the events of Book #30. Marco's father Peter, still believing her dead from the "boating accident" several years earlier, marries Nora Robbinette, Marco's math teacher. The stress from his father's actions cause Marco's morphs to go haywire, the results from his morphs are (in order of appearance): an osprey crossed with a lobster, a trout with the arms of a gorilla, a wolf spider crossed with a skunk (a "Skider" or "Spunk" as Marco called it), and finally a poodle and a polar bear (a Poo-Bear as Marco called it). The Yeerks try to use a popular TV icon named William Roger Tennant to try and persuade people to join The Sharing, but the Animorphs expose him on national TV when he is terrorizing Marco who is in poodle morph, which ruins Tennant's reputation.

The book ends with Marco getting a phone call from Visser One, which is covered in greater detail halfway through Visser.

Marco's father marries Nora.

Jake -Squirrel, cockatiel, Siberian tiger, seagull, cockroach, flea, peregrine falcon, housefly.

Rachel -Squirrel, cockatiel, grizzly bear, seagull, cockroach, flea, bald eagle, housefly, wolf .

Tobias -Cockroach, flea, seagull, human (himself) .

Cassie -Seagull, squirrel, cockatiel, wolf, cockroach, flea, osprey, housefly .

Marco -Osprey–American Lobster hybrid, seagull, squirrel, cockatiel, Silverback gorilla–trout hybrid, Silverback gorilla, osprey, wolf, housefly, cockroach, wolf spider–skunk hybrid, poodle, great horned owl, poodle–polar bear hybrid.

Ax -Human (main), squirrel, cockatiel, seagull, cockroach, northern harrier, housefly.

The front cover quote is, "What's on your mind...?"

The inside front cover quote is, "Man's best friend? Not this man...."