We are in England in the 1660s, Charles II has been restored to the throne following years of civil war and Oliver Cromwell's short-lived republic. Oxford is the intellectual seat of the country, a place of great scientific, religious, and political ferment. A fellow of New College is found dead in suspicious circumstances. A young woman is accused of his murder. We hear the story of the death from four witnesses: an Italian physician intent on claiming credit for the invention of blood transfusion; the son of an alleged Royalist traitor; a master cryptographer who has worked for both Cromwell and the king; and a renowned Oxford antiquarian. Each tells his own version of what happened. Only one reveals the extraordinary truth.