While dealing with people from their past and treachery from unexpected sources, Tom, Hester, and Wren return to save the world.

In the distant future, when fifteen-year-old Wren Natsworthy, bored with life in Anchorage, steals an Old-Tech book for a Lost Boy, she sets off a sequence of events that leads her parents, Tom and Hester, back into battle with old enemies and new.

A young colonist on Mars befriends a strange round creature called Willis who gets him into trouble when he goes away to school, but whose presence and friendship finally enable the colonials to negotiate a treaty with the Martians.

Commander Toad and the crew of Star Warts are asked to rout out Tip Toad, Space Fleet's greatest and most elusive spy.

Tobias has gotten used to his new life. He's a red-tailed hawk with the mind of a kid. It was difficult when he first became trapped in his morph, but he's started to come to terms with things. After all, how many kids actually get the chance to fly?But now Tobias is about to make a very difficult choice: a choice that the other Animorphs know nothing about. And it could mean the difference between living the rest of his life as a hawk...and being...

In a world which has banned self-aware robots, Eager and his brilliant but headstrong nephew, Jonquil, come out of hiding to visit the Bell family, and soon become involved in the mysterious and dangerous events surrounding them and their friends.

In futuristic Satellite City, fourteen-year-old Cosmo Hill escapes from his abusive orphanage and teams up with three other people who share his unusual ability to see supernatural creatures, and together they determine the nature and purpose of the swarming blue Parasites that are invisible to most humans.

While backpacking in the desert, thirteen-year-old Mark falls into a tube of blue light and is transported into a more primitive world, where he must use his knowledge and skills to survive.

When his boy soprano voice begins to change, Piemur is drafted by Masterharper Robinton to help with political work and is sent on missions that lead him into unusual and sometimes dangerous adventures.

When thirteen-year-old Luke Garner unwittingly sets off a rebellion which sweeps the country and ousts the Population Police from power, he quickly realizes that the new regime is corrupt and he may hold the only key to true freedom.