A Wizard Alone — Diane Duane

Becoming a wizard isn't easy. In fact, it can kill you.

All first-time wizards must go through an initiation in magic called an Ordeal. Most last only a few days. So why has Darryl McAllister been on Ordeal for three months?

Or has he? Darryl hasn't actually gone anywhere. His body is still here; it's his mind that seems to have departed. And that's where Kit and Nita come in. Only together can they unravel the mysteries around Darryl -- who he is, what he is, and why the source of all death in the universe, the Lone Power, is desperately trying to destroy him.