Charlie Red
(Book)

"Tom Slade is riding shotgun for the Colorado and Prescott Stagecoach Company, in charge of delivering $45,000 in cash to the mines in central Arizona, when the stage is robbed at an isolated way station. Most men would have gone on to Prescott for help, but Slade knows he doesn't have that kind of time if he hopes to catch up with the thieves before they disappear into the desert. Alone and riding a worn-out harness mule, Slade grimly sets off in pursuit. He realizes it’s going to take every ounce of skill and perseverance he’s got to recover the mine payroll and bring the bandits to justice. What he hadn't counted on was a woman named Claire Adams showing up in the middle of the desert with her own reason for tracking down the outlaw gang, or the influence of her mysterious friend, Charlie Red." -- Amazon.com.