An ingenious tour de force: an utterly compelling historical mystery with a plot that twists and turns and keeps the reader guessing until the very last page.

We are in England in the 1660s. Charles II has been restored to the throne following years of civil war and 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.