An elusive killer targets couples in the dead of night - murdering the women and leaving men with their memories wiped clean. Private investigator Riley Sullivan faces her toughest case yet, and this time it's personal. Her friend and business partner, Cooper Deagnan, is a suspect when he wakes to find a dead woman next to him in his bed.

The murder pits Cooper against his friend, Det. Luke Morgan, for the first time in his life. Recovering his missing memories might be the only hope to stop a killer whose reign of terror has only just begun.

No matter whose side they are on Riley and Luke must use every resource they have to stop a serial killer who leaves few clues, increasingly frenzied crime scenes, and complicated witnesses who have little information to share. Can they catch a killer who no one remembers?