Fergus MacBeath has inherited from his Highland family rare skills as a healer and perhaps other esoteric knowledge. He is rescued from near-fatal injury at Soltre Abbey Hospital, and in time becomes the chief physician there, the medicus. With seeming supernatural abilities, he is regarded among the
country people as a saint.

He is a maverick however and defies Church orthodoxy relating sickness to sin, using Soltre's wealth, bequeathed over centuries, for the welfare of the Borders people. The lands and possessions are coveted by Church and State, who plot to seize them, but Soltre seems to be immune from their intrigues.

Until - Fergus falls disastrously in love. Suddenly the defences of the sanctuary are breached as royal greed and divine paranoia conspire, unleashing savage and unholy violence. Who will survive the wreckage?