An exciting thriller spanning the years from Roman Britain to modern day Manchester. In AD70 a squad of crack Roman troops follows a band of Celtic Warriors into the mountains of North Wales, only to be slaughtered by a mysterious enemy who attack from the mist. In 2008, archaeologist Elsa Chirk discovers an account of the massacre, which leads her into mystery dating back centuries. In 2012, a mutilated body is discovered in an alleyway in Manchester. DCI Owain Davis investigates and finds himself drawn into the mystery.