Cowboy State Lawmen: Duty and Honor Series by Juno Rushdan

His past has left him scarredBut then comes a chance at redemption…Rescuing teenage campers from a fire left Liz Kelley scarred for life. But her Wyoming town isn’t all she left behind. Fire marshal Sawyer Powell can’t forgive himself for failing to protect her that terrible night. Fifteen years later, a string of suspicious fires brings Liz—now an FBI agent—home. Working the case together gives the former lovers a second chance—but also makes them a killer’s target.