A simple quest to establish the identity of a strange, confused girl leads Colonel Robert De Waal to a place that seems to be frozen in the horrors and terrors of its past. Armed with the scanty information that the girl has given him and with the assistance of disgraced historian, Gordon Dewhurst, De Waal must unravel the mysteries that lie hidden in the darkness below the surface of an ancient builder's tomb. Who is the strange girl who calls herself, Carrie Martins? Is she just a runaway schoolgirl or is she a young nun with a reason to be bitter? Or do they hold the key to a series of sinister events and brutal murders?