Professor Alice Roberts embarks on an adventure across Britain to decode the truth behind its Holy Grail legends, linking Arthurian lore, sacred relics and the Knights Templar. She begins on the Isle of Wight, exploring the story of Joseph of Arimathea and the Grail. Did Joseph bury the Grail beneath the Tor? Archaeologist Cheryl Green and Dr Andrew Boakye help assess the legend's historic plausibility.