Satan's Fire (Hugh Corbett Mysteries, Book 9): A deadly assassin

1303 and the Old Man of the Mountain remembers back to when he nearly killed Edward I thirty years before. He now decides to release an imprisoned leper knight to avenge old grievances and take the King's life. A few months later two nuns are returning to their monastery in York, where they are confronted by the horrific sight of a man being consumed by fire, the sickly smell of burning flesh lingering in the air. News of the grisly death greets Edward as he arrives in York for secret negotiations with the leaders of the military Templar Order. His unease deepens when an attempt is made on his life. When the assassin, wearing Templar livery, is found dead - having been engulfed by a mysterious fire - Edward immediately turns to his Keeper of the Secret Seal, Hugh Corbett, to investigate.