Impressed by the proud caterpillar's boast that she will turn into a butterfly when she grows up, a polliwog determines to watch the caterpillar very carefully and turn into a butterfly too.

The Yeerks aren't playing around anymore. They're no longer hiding behind a silent invasion. And one of the first steps in their new plan is to take over the National Guard, to prepare for all-out war against humanity. Marco and the other Animorphs couldn't be less prepared for this news. The Yeerks know who they are, forcing them to hide to protect their families. Things are falling apart, and for once Jake may not be able to make the decision that...

The Animorphs have been split up before. And they've had to fight battles without one another. But this time is very different. Not only is Cassie totally alone, she's managed to find herself in Australia. In the rural Outback. The other Animorphs don't even know she's there. Cassie doesn't have any idea where she's going, or if she can even survive the rugged terrain. But she does know she has to get to a town or village and contact her family...

Rachel is captured by David, the sixth Animorph who was once trapped and left on a deserted island. He's back and wants revenge.

The arrival of Andalites on Earth gives Ax and the Animorphs allies to fight against the Yeerk invasion but also causes new poblems.

David, the newest Animorph, is not what he appears. His need to control the other Animorphs is all he thinks about. And the things he does are starting to break up the group. Rachel and the others know that time is running out. The newest battle against the Yeerks is the most important one yet. And it's not one that will wait. Winning this fight could mean slowing down the invasion. But no one knows what to do with David. Because the newest Animorph...

One Thursday Imogene wakes up with a pair of antlers growing out of her head and causes a sensation wherever she goes.

When the Animorphs try to stop the tiny alien Helmacrons from taking the morphing cube, Marco gets in the way and ends up with Helmacrons up his nose and inside his head.

Ax and the Animorphs discover that Visser One is overseeing a secret underwater project.

Jake has made an amazing discovery: a web site about the Yeerks. Should the Animorphs investigate? If they do, they might walk right into a trap. And if they don't, they'll never know if they're fighting their enemies alone.