The frontier zone of Archenfield in Herefordshire is a no-man's-land, which acts as a bulwark between Norman-controlled English soil, and the Welsh border. Soldier Ralph Delchard and lawyer Gervase Bret arrive in Hereford for what looks like one of their more straightforward assignments from the crown, to settle conflicting claims to land in Archenfield. Ralph and Gervase are shocked to discover the murder of a principal witness, a wealthy landowner who was burned alive in his own home. No clues remain except an enigmatic red dragon cut into the turf in front of the house.