Robert Carlyle stars as James I, who battles with the Catholic conspiracy against him and eventually foils a plot to blow up the Houses of Parliament. The Gunpowder Plot was masterminded by the influential Catholic Robert Catesby (Richard Coyle) and planned by Guy Fawkes (Michael Fassbender), who wanted to rid the nation of an oppressive Protestant monarch. Clémence Poésy plays James I's mother, Mary Queen of Scots, who spends most of her short reign locked in a battle with both her Protestant subjects and the English Queen, Elizabeth I (Catherine McCormack), before conspiring with the Earl of Bothwell (Kevin McKidd) to assassinate her miscreant husband Lord Darnley (Paul Nicholls).