The Black Book (A Black Book Thriller).

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.