When cowboy Lefty Brown witnesses the murder of his longtime partner, the newly-elected Senator Edward Johnson, he strikes out to find the killers and avenge his friend's cold-blooded murder. Tracking the outlaws across the vast and desolate Montana plains, Lefty stumbles across a young wannabe gunslinger, Jeremiah, and an old friend, a former hard-drinking pal turned U.S. Marshal, to help deliver the men to justice. After a gunfight with the outlaws leaves Jeremiah wounded, Lefty returns home with the names of Johnson's killers only to find that he is being accused of his friend's murder by the governor. With the tables turned Lefty must evade the law, get the Marshal to stop drinking again, and prove his innocence by exposing the powerful men ultimately responsible for Johnson's death.