Billy Harney was born to be a cop. The son of Chicago's chief of detectives, whose twin sister is also on the force, Billy plays it by the book. Alongside Detective Kate Fenton, Billy's tempestuous, adrenaline-junkie partner, there's nothing he wouldn't sacrifice for his job. Enter Amy Lentini, a hard-charging assistant state's attorney hell-bent on making a name for herself-who suspects Billy isn't the cop he claims to be. They're about to be linked by more than their careers.