What starts as a routine stabbing for DI Jed Parish and PC Mary Richards turns into the hunt for a serial killer who uses an unusual weapon to kill, and leaves numbered tokens in his victim's mouths. As well as getting to know each other and dealing with the fallout from the Chief's prostate cancer, the two new partners must discover the dark history behind the tokens and the connection between the victims. To do that, they must gain access to the abandoned Beech Tree Orphanage where a terrible truth awaits.