The dangerous, emotional and arduous toll of stealth ops has never been felt more deeply than by those who adopted completely separate personas to integrate themselves into a shadowy underworld. From "The Pond", an intelligence operation so secret the CIA was kept in the dark, to a luxury Red Sea diving resort covertly operated by Mossad agents, to the British security services' daring rescue of a double agent in Moscow. These undercover smokescreens were all driven by daring agents in service of executing a greater purpose.