Brimstone

In the third novel of Robert B. Parker's Appaloosa series, Virgil Cole, unable to get over the adulterous Allie French, travels with his gun-for-hire partner and good pal, Everett Hitch, to find her, scouring the unforgiving southwest. Finally, at a small-town brothel, the men find her, and the three head north to start anew in Brimstone. There, Virgil and Everett secure positions as the town's deputies, while Allie seeks redemption for her sins...