A controversial priest dies suddenly on the steps of the great cathedral, moments before his long-awaited restoration after years of excommunication. Church leaders hail his death as a divine sign.

But Captain Aurelius - the trusted imperial aide assigned by Constantine himself to investigate - is not convinced. Was this truly an act of God, or the work of someone far more earthly? As he retraces the priest's final moments and unravels the decades of disputes that made the man a target, Aurelius uncovers secrets capable of igniting civil war in both the Empire and the Church.

Named for the philosopher-emperor of earlier days, Aurelius soon realizes that the future of his world may hinge on what he discovers. And as the lines between faith and ambition blur, he must confront a question more dangerous than any enemy.

Is his world being led by saints... or by demons?