Trouble on the Mountain — L.A. Moore

When his mentor asks U.S. Marshal Grover Rayborn to escort a gang leader from Laramie to Denver for trial, he readily agrees. What was supposed to be an easy trek through a mountain pass turns into a desperate fight for survival when Marshal Rayborn encounters an angry ex, a vengeful widower and a cold blooded assassin.
And that's just the beginning of his troubles.