John Gerard was born in 1564 into Lancashire nobility at a time when keeping the Catholic faith in England was treated as a threat to the crown. When he was five, his father, Sir Thomas Gerard, was jailed for plotting to rescue Mary, Queen of Scots, and the boy was placed with Protestant relatives while a secret Catholic tutor went on teaching him. He left for France at 12 to get the education barred to him at home, was arrested at Dover on his return for lacking a travel permit, and spent more than a year in the Marshalsea before Anthony Babington posted his bail in 1585.

After joining the Jesuits in Rome, Gerard landed in Norfolk in November 1588, three months after the defeat of the Spanish Armada, and survived by refusing to look like a priest. This episode follows his years as the fashionable, gambling, falcon-flying Mr. Thompson, the network of safe houses and priest holes he helped build, his capture in 1594, and the night of October 4, 1597, when he crossed the Tower moat on a rope with hands wrecked by torture.

• Some priest holes measured as little as one meter tall and half a meter wide, and searchers would occupy a house for days hoping to starve out whoever was hidden.
• In the Tower he was hung by manacled wrists for hours to make him reveal the whereabouts of Henry Garnet, leader of the English Jesuits, and he gave up nothing.
• Nicholas Owen, the builder of many priest holes, masterminded the escape, and Gerard persuaded his own jailer to come down the rope with him.
• In May 1604 he said mass at the Duck and Drake Inn for Robert Catesby and others who had just sworn themselves to the Gunpowder Plot, a fact that later made him a prime suspect.
• He outlasted a nine-day search inside a hiding place, wrote a refutation of the charges that was printed and scattered around London, and left England disguised as a footman of the Spanish ambassador.