How to Be Bad — David Bowker

Mark is a mild-mannered twenty-three-year-old bookseller who makes endless lists about stupid things. His life changes when he reestablishes contact with his old girlfriend, Caro. At seventeen, Caro was an implausibly sexy, promiscuous, druggy big-mouth. Six years later, she's exactly the same and Mark falls in love with her all over again. Caro, who has nothing but contempt for Mark's list and his choirboy attitude, asks him to prove his love by giving him a list of her own: a list of people she wants him to kill for her. As things begin to spiral out of control and the bodies pile up, Mark himself becomes a target and realizes that to survive, he needs to be as ruthless and decisive as his enemy.
Violent, edgy and with a wicked sense of humor, How to Be Bad establishes David Bowker as one of the premier crime writers working today.