2 Sisters Detective Agency

From the world's #1 bestselling author comes a thrilling novel where a detective duo of sisters finds themselves in the crosshairs of a dangerous and lawless group.
Attorney Rhonda Bird returns home after a long estrangement when she learns her father has died. There she makes two important discoveries: her father stopped being an accountant and had opened up a private detective agency, and she has a teenage half sister named Baby. Baby brings in a client to the detective agency, a young man who claims he was abducted. During the course of the investigation, Rhonda and Baby become entangled in a dangerous case involving a group of overprivileged young adults who break laws for fun, their psychopath ringleader, and an ex-assassin victim who decides to hunt them down for revenge.
"She was a killer. Jacob Kanular knew it, as soon as the girl put the gun to his head. It was the way she angled the barrel of the revolver: straight down from forehead to neck so that when she pulled the trigger, the bullet would pass cleanly through his brain to his spinal column. She wasn’t trying to scare him. Wasn’t messing around by putting the gun against his temple or his mouth. Whoever she was, she knew how to kill."