Book III of The Amtrak Wars. It is 2990 A.D. The centuries-old conflict between the hi-tech underground world of the Trackers and the primitive, surface-dwelling Mutes continues with unabated ferocity.  Steve Brickman is torn between two cultures and is on his most dangerous mission:  The rescue of Cadillac and Clearwater, two gifted Mutes held captive by the mysterious Iron Masters.