In the wake of the 1588 destruction of the Spanish Armada, English Catholics launched an ingenious counterespionage effort to undermine the Tudor government's anti-Catholic machinations. This Jesuit-connected network secretly transmitted intelligence to Brussels, Antwerp, Madrid and Rome. Its central figure was William Sterrell, a brilliant Oxford philosopher. Sterrell moved at the highest levels of government, working for the ill-fated Earl of Essex and for the powerful 4th Earl of Worcester, secret sponsor of the Jesuits. This is the story of Sterrell's secret network--undetected for 400 years--brought to life in vivid detail, based on close examination of hundreds of original letters and documents never before transcribed or published.