In the middle of an important investigation, Smoke Tree Substation Commander Carlos Caballo, known up and down the Colorado River Valley as "Horse," is suddenly called away to find a man who has shot an inspector at the California Agricultural Inspection station in the tiny desert community of Vidal, California. A California Highway patrolman has found the car abandoned alongside Highway95. When Horse and and the patrolman force open the trunk, they discover a body: the man's wife. Horse realizes he and his deputies must find a killer who is on foot in the vast, unpopulated area where the Mojave and Colorado deserts meet. During the hunt, they encounter a mysterious and self-sufficient Native American who becomes an important part of the pursuit.