Cuff Me, Sheriff by Katie Douglas

Agent Mariella Frost has a cold heart, especially when it comes to the holiday season. Her perfect Christmas is overtime. When she’s sent to Snake Eye to investigate a drug cartel of snowbirds, she’s thrust straight into a world run by unyielding, stern, Bob Halsey, who she takes an instant dislike to.
Bob lost the love of his life in a shoot out two decades ago, but the pain flares up every winter. When Mariella shows up, they don’t hit it off straight away, but when someone in his town gets hospitalized from a new, dangerous party drug, he has to work with her to solve the crime.
But Bob won’t take any nonsense from some city girl with an FBI badge. When she threatens the case, he bends her over his desk and takes his belt to her. He will show her exactly whose law it is out here.
But the case starts to look hopeless. Can they catch their perp before any more kids get hurt?