The Last Horseman - Frank Zafiro

Sandy Banks is the last of The Four Horsemen, a vigilante group of ex-cops determined to right the injustices of a broken court system. But now the project is disintegrating, putting him in the middle of chaos. Betrayed by his final partner, blackmailed by the project head and pursued by federal agents bent on busting the case wide open, Sandy scrambles to escape this mayhem with his soul intact.
From the author of the River City crime series.