London, 1605. Robert Catesby, a 33-year-old Warwickshire gentleman, devises a plot to blow up Parliament and and kill the king.
England, 1603. Elizabeth I is dead and King James of Scotland has taken the throne. With the country at war with Catholic Spain, English Catholics are persecuted and priests caught saying Mass are punished with death. Several attempts have already been made on the new King's life. All so far have failed. But deep in the heart of the Warwickshire countryside a new plot is brewing. A plot that will become legend, and leave a mark on the country that will still be felt over 400 years later.
On the eve of the 5 November, Catesby, Fawkes and the plotters load the tunnels below Parliament with barrels of gunpowder.
Across the city, Father Garnet is under pressure from an ally to break his seal of confession and reveal Catesby's plot - for the good of the Catholic faith. Will the priest be the one to betray Catesby at the eleventh hour? Or will Cecil need to find other means to destroy Catesby, win back the King's trust and save his life?