It is easy to see why double agents are the source of inspiration for many spy novels and movies. The intrigue involved, including a potentially violent end to their spy games, gives writers low-hanging fruit to pluck. But art frequently mirrors real life when it comes to double agents. Especially infamous examples were found out during the Cold War – on both sides of the fight. And every secretive group on the planet, from intelligence agencies to terrorist organizations, must worry that double agents are among their ranks.

Al Qaeda has been especially paranoid about the use of double agents, as can be seen in the group’s literature dealing with counterintelligence and operational security. Even before 9/11 the group would beat and torture any man the most senior terrorists suspected of being a spy posing as an eager recruit. In order to gain admittance to an al Qaeda safe house, terrorists needed someone in the organization to vouch for them if they were not already known to the house’s inhabitants.