Their cowboy days behind them—though they'd never get the cow smell out of their Levis—and Pinkerton badges in their pockets, Bill Robuck, Happy Jack Dean, and Laughing Ed Leffler ride the owlhoot trails from Canada to Mexico, a collective scourge to desperadoes and rustlers.
They live by the code "One for all and all for one" until they arrive in Flathead and a treacherous trail opens before them, proving to Robuck that even a partner can't be trusted. Robuck rides that trail to its last long mile, and transforms it to a trail of vengeance. His work done, embittered as only a man can be who's been sold out by his best friend, he's ready to move on, weary of gunsmoke and wanting only to forget. But the days of drifting and moving on are over, for in that valley of treachery and bushwhack death is girl who's the end of all trails for him.