Passport (S02E01)

Hannah gets the chance to explore a highly classified facility where anonymous personnel and cutting-edge technology are dedicated to ensuring that the British passport ranks among the world's most secure documents. She uncovers the World War I espionage techniques embedded within each passport's pages and delves into the evolution of modern identification processes, influenced by the pursuit of a 19th-century French serial killer and the vibrant psychedelic art of the 1970s.