Amazon.com Product Description (ISBN 0441644651, Paperback)

Out of print no longer: Book Four of the Apprentice Adept series--from the New York Times bestselling author.

Two worlds--the scientific Proton, and the magical Phaze--exist side-by-side. Now, Mach has crossed from Proton to Phaze, switching places with his counterpart Bane. And both must learn to survive in environments alien to their own nature.