Fleeing the massacre of most of his family, young aristocrat Quintus Varrus arrives in fourth-century London not knowing who is to blame for the murders or who he can trust. He meets a young Irish woman named Lydia Mcuil and their lives quickly become intertwined and her father offers to set Quintus up as a smith while the young lovers get to know each other from a distance. But the assassins still hunt Quintus and a deadly ambush is barely avoided, but he does become friends with his rescuer, a military policeman known as Rufus Cato. Quintus learns the secrets of a powerful, ancient brotherhood, as well as secrets that may finally reveal the identity of those who murdered his family, and the shocking reason why.