On 5 November 1605, an audacious plan to decapitate the British state was foiled when Guy Fawkes and nearly a ton of gunpowder were discovered in an undercroft beneath the House of Lords. The plan was to blow up King James I and the majority of the nation's religious and political leadership during the State Opening of Parliament and incite a Catholic uprising across the country. It was hatched by a group of disillusioned Catholics, led by Robert Catesby, in a bid to end Catholic persecution and install a monarchy friendly to what they believed to be the true faith. With the discovery of Guy Fawkes, the plot was foiled and many of its participants met bloody ends at the hands of the vengeful authorities. On the anniversary of the plot, better known as Guy Fawkes Night, Dan explains how and why the conspiracy came about, why it failed, what the impact of the plot was and why it has become so embedded in Britain's national identity.