Book 1

Rainbow Abyss

by Barbara Hambly

Published 8 August 1991

Book 2

Magicians of Night

by Barbara Hambly

Published 13 January 1992
Alone in the world of 1940 Germany, Rhion finds himself used and manipulated by the four would-be wizards of the Occult Bureau, who need him in their mission to defeat the enemies intent on conquering their fatherland.