A chewed-up corpse high in the Flat Tops Wilderness Area leaves Colorado hunting guide Allison Coil mystified. Obvious signs suggest the dead man is the victim of a mountain lion attack, but Allison's instincts tell her otherwise. Miles away in downtown Glenwood Springs, a controversial candidate for U.S. Senate is shot during a campaign stop as newspaper reporter Duncan Bloom watches, dodging the long-range gunfire. Trapline follows Coil and Bloom as their investigations collide, exposing the dark depths of human indifference.