The invasion - K.A. Applegate (Animorphs #1)

We can’t tell you who we are. Or where we live. It’s too risky, and we’ve got to be careful. Really careful.

The thing you should know is that everyone is in really big trouble. Yeah. Even you.

Sometimes weird things happen to people. Ask Jake. He may tell you about the night he and his friends saw a strange light in the sky – and ended up on a mission to save the human race.

That night Jake, Rachel, Cassie, Tobias and Marco were given the power to morph into any animal they choose. And now they must use that power to outsmart an evil that is greater than anything the world has ever seen…