This is a very big problem for Jake's brother, Tom. He can't be away from the Yeerk pool for that long. So Tom refuses to go -- and his father insists. But Tom's Yeerk will do anything to survive. Including making his father less of a problem.

Now Jake, the other Animorphs, and Ax have to find a way to protect his father without Tom discovering their secret. And without having to choose between his father's life...and Tom's.