Different Lies To Find The Spy

Someone is a spy. But how to find them? This trope is about one solution. Tell multiple people different related similar lies, and then see how the person the spy works for reacts. It may be worth noting that doing this doesn't inherently prove that the information leak is actively trying to act as a spy, maybe they just have Loose Lips and their spouse is the actual spy or something. But usually the leaker is a spy.

Fan Works

 * Jenny does this in A Young Girl's Delinquency Record.

Live-Action TV

 * Tyrion Lannister determined that Pycelle works for Cersei this way in Game of Thrones

Western Animation

 * Tina Belcher did this in the Bob’s Burgers episode Tina Tailor Soldier Spy