The Black Book (A Billy Harney Thriller, 1)

The "thrilling" #1 New York Times and USA Today bestseller (Karin Slaughter): when three bodies are found in a Chicago bedroom, a black book goes missing . . . and the city has never been more dangerous.
Billy Harney was born to be a cop. As the son of Chicago's chief of detectives with a twin sister on the force, Billy plays it by the book. Teaming up with his adrenaline-junkie partner, Detective Kate Fenton, there's nothing he wouldn't sacrifice for his job. Enter Amy Lentini, a hard-charging assistant 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.
A horrifying murder leads investigators to an unexpected address-an exclusive brothel that caters to Chicago's most powerful citizens. There's plenty of incriminating evidence on the scene, but what matters most is what's missing: the madam's black book. Now with shock waves rippling through the city's elite, everyone's desperate to find it.
As Chicago's elite scramble to get their hands on the elusive black book, no one's motives can be trusted. An ingenious, inventive thriller about power, corruption, and the secrets that can destroy a city, The Black Book is James Patterson at his page-turning best.