During the early 17th century, Europe was gripped by the Reformation and Counter-Reformation, when Catholics and Protestants persecuted each other with equal fervor. England was ruled by a Protestant regime, and in 1605 a group of oppressed Catholic landowners hatched a plot to kill King James I, during the opening of parliament on 5 November. The plan, devised by Midland Catholics Robert Catesby and Thomas Wyntour, was to blow up the Houses of Parliament with dozens of barrels of gunpowder. Known as the Gunpowder Plot, it was foiled at the last moment when conspirator Guy Fawkes was discovered nervously waiting to light the fuse. When Fawkes was tortured into revealing the names of the other conspirators, the small band of conspirators fled to the Wyntour family home at Huddington Court in Worcestershire. Here they spent their last night, fleeing a few miles the next day before being surrounded by militiamen. But the story didn't end here. The king's chief minister, Robert Cecil, had given strict instructions that Robert Catesby should be captured alive. The reason was that he possessed a sacred relic: a green jade gemstone called the Meonia Stone. According to tradition, it was once embedded in King Arthur's sword Excalibur. It had historically belonged to Mary Queen of Scots, the last legitimate Catholic heir to the English throne. After his death in 1587, a legend had developed that the Catholic who would finally secure the English throne was supposed to possess the sacred stone. Fearing that the Meonia Stone would serve as a rallying symbol for English Catholics, Cecil was determined to destroy it. He was furious, however, to discover that Robert Catesby had been shot dead and knowledge of the stone's whereabouts had died with him. Despite months of frantic searches and intense interrogations of the surviving conspirators, the stone was never found. Three centuries later, in 1979, Graham Phillip and fellow researcher Andrew Collins decided to go in search of the lost Meonia Stone. The Green Stone, written in collaboration with Martin Keatman, is the extraordinary true story of this fascinating research. Following a trail of historical clues, Graham and Andrew finally discovered the identity of the person to whom the stone was given. During their interrogation, the survivors of the Gunpowder Plotters had stated that Robert Catesby still had the stone with him the night before his death..