Sequel to Hambly's Windrose series. A transport corporation in another dimension has run a trans-dimensional transport corridor through Los Angeles, and is powering it by draining the psychic energy of the population in its path, driving large numbers of people temporarily insane. Exiled wizard Antryg Windrose and his partner, computer programmer Joanna Sheraton, attempt to put a stop to this by hacking into the corridor itself with a combination of computer technology and magic, assisted by a renegade mage from Antryg's own world.