Relentless — Brian Garfield

A Native American sheriff chases a gang of bloodthirsty bank robbers Were it not for the copper mine, San Miguel wouldn't exist. A hardscrabble town hewn out of the Arizona desert, it's long on sand and short on excitement. For fun its citizens go to Las Vegas twice a month, just after picking up their paychecks. Because most of the miners take their pay in cash, every two weeks more than a million dollars moves through San Miguel's little bank, watched over by heavy security from the sheriff's department. This week, the security is not strong enough. A team of shotgun-wielding men burst into the bank. They disable the guards with mace, killing one, and leave with the largest bank haul in Arizona history. Sam Watchman, a Navajo state trooper, is on their trail. But these men aren't just robbers; they're psychopaths. Watchman is in for the hunt of his life.