Number two in the Dublin Murder Squad series by Tana French. Cassie Maddox has transferred out of the Murder Squad, but gets an urgent call to attend a crime scene. The murder victim is Cassie's double and is identified as Alexandra Madison. However, Alexandra Madison doesn't exist; the name and persona was made up for Cassie in an undercover assignment. Cassie once again goes undercover to find out who this girl was and who killed her. She may just lose herself along the way.