Ambush by Frank McCarthy.

 

Print released 1998.

 

Somewhere, over the shoulder, out there, an enemy of unknown numbers begins their attack in quest of gold, payroll or passenger's jewels. The cavalry troopers and stagecoach driver galvanize into immediate action. All in an arid landscape of time-worn rocks, dust that obscures the unseen adversary, and heat shimmer that accentuates this cast of characters in a race with mortal danger.