This Girl's a Killer - Emma C. Wells

For readers of Finlay Donovan is Killing It and The Bandit Queens comes a bright and biting thriller following Cordelia Black, a best friend, a businesswoman, and, in her spare time, a killer of bad men.
Ask Cordelia Black why she did it. The answer will always be: He had it coming.
Cordelia Black loves exactly three things: Her chosen family, her hairdresser (worth every penny plus tip), and killing bad men.
By day she's an ambitious pharma rep with a flawless reputation and designer wardrobe. By night, she culls South Louisiana of unscrupulous men—monsters who think they've evaded justice, until they meet her. Sure, the evening news may have started throwing around phrases like "serial killer," but Cordelia knows that's absurd. She's not a killer, she is simply karma. And being karma requires complete and utter control.
But when Cordelia discovers a flaw in her perfectly designed system for eliminating monsters, pressure heightens. And...