In the heart of the Terran colony on Darkover, a deadly outbreak of Trailmens Fever threatens to wipe out the population. Time is running out, and the only chance for survival lies in developing a serum‚Aîif they can secure the cooperation of the enigmatic native Trailmen and the brilliant yet troubled parasitologist Dr. Jay Allison, who grapples with his own split personality. Will they unite in time to save the colony? (Introduction by Mark Nelson)