Different Lies To Find The Spy

Everything About Fiction You Never Wanted to Know.
I told Varys I was giving the princess to the Greyjoys. I told Littlefinger that I planned to wed her to Robin Arryn. I told no one that I was offering her to the Dornish, no one but you.
—Tyrion Lannister, Game of Thrones

Someone is a spy. But how to find them? This trope is about one solution. Tell multiple people different, but 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.

Examples of Different Lies To Find The Spy include:

Advertising

Anime and Manga

Comic Books

Fan Works

  • Jenny does this in A Young Girl's Delinquency Record. After she accuses Stevie, Stevie makes a run for it. Jenny interprets the running as a confirmation that Stevie was an informant for the police (instead of there being a coincidence), and then presumably kills him in front of her other subordinates to make an example of him. At the very least, she hurts him enough to get blood on her knuckles.

Film

Literature

Live-Action TV

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

Music

New Media

Newspaper Comics

Oral Tradition, Folklore, Myths and Legends

Pinball

Podcasts

Professional Wrestling

Puppet Shows

Radio

Recorded and Stand Up Comedy

Tabletop Games

Theatre

Video Games

Visual Novels

Web Animation

Web Comics

Web Original

  • Done in Fenspace during the "Boskone War", in order to root out which group in the allies was leaking secrets to the enemy. Each group was told to rendezvous at a different location; when the enemy forces showed up early at one location to ambush the allies, the allies knew where the leak was.

Western Animation

Other Media

Real Life

  • Who leaked the spoiler that Spock was going to die in Star Trek II: The Wrath of Khan? Thanks to somebody making sure each script had a unique code - in essence, something different was told to each person involved - we know that it was Gene Roddenberry himself.