Books in the Gunslinger series

Shortly after finding a murdered man with a strange brand on his forehead, Connor and Abby Mack, along with their mentor, River Hicks, come to the aid of a black settler being menaced by a band of gunmen.

Gunman River Hicks, along with twins Connor and Abby Mack, his wary teenage trail companions, stop in Abilene to catch their breath. But when Abby kills the sheriff's son in self-defense, they are forced to flee to Colorado, pursued by a vengeful posse.