Abstract: During the trial of the so-called Powder Men--Guy Fawkes and his co-conspirators in the Gunpowder Plot to blow up Parliament with the King, Queen, and heir apparent all in attendance-the King's Attorney General Sir Edward Coke presented into evidence a curious manuscript with two titles. The text's original name was A Treatise of Equivocation, but that had been scratched out and replaced with a new title, A Treatise Against Lying and Fraudulent Dissimulation. It had been discovered in the rooms which one of the conspirators had used in the Inner Temple, and mere possession of this book, Coke clearly thought, spoke loudly of all the defendants' guilt. By delaying the trial long enough to secure this manuscript, Coke ensured that he would be able to continue in a prosecutorial tradition he had established in the trial of the Jesuit Robert Southwell - a tradition of proving treason against English Catholics by representing them as ready equivocators. The Treatise of Equivocation was written to instruct priests sent on a "mission" established by the Society of Jesus, whose aim was to preserve the Catholic Church in the newest heathen territory, England. The Treatise prepared priests to face the perilous questions asked of them by official interrogators, who as enforcers of the Anglican settlement had devised a series of interrogatories widely known as the "bloody questions" because they could force a Catholic priest to elect between the Queen and the Pope. The stakes were high: the penalty for being a priest in England, an act of treason, was death by public torture.