A character — more often than not female — is revealed to be a traitor.
She however has a "Get out of Jail Free" Card. Her love interest, family member, child, woman's equivalent of a mistress, or cat has been arrested by the Secret Police in Commie Land and unless she helps them, they'll be finding a very familiar severed head in their mail. Maybe it's Martians that want a human to do their probing for them, or it's a crack dealer who wants his arrest records off the books, or maybe it's a needlessly complicated plot for love.
Somewhat of a Truth in Television, as death threats to loved ones does often provide incentive to do one thing or another. However, in a world of common sense, most incidents like these would be reported to the police. Hopefully.
WARNING: Due to the nature of this trope, everything below is a spoiler and may not be suitable for everyone. Viewer's Discretion is Advised.
- In Food Wars!, Akira Hayama joins Central and works to help them break apart the student rebellion, which earns him the scorn of Soma, who thought he was honorable. Turns out he joined Central because the dean threatened to delete his adoptive mother's research data and shut down her laboratory, which would destroy 30 years of her life's work. His defection doesn't last long, though; he promptly returns to the side of good when he loses a Shokugeki to Soma and his mother calls him out for joining Central.
- In a Marvel What If? where the Submariner joined the Fantasic Four and married Sue, Reed Richards hired a lab assistant whose family was being held hostage by Doctor Doom. (She does help foil Doctor Doom's plan and save Reed's life before he married her.)
- Several Buck Danny stories have one of the squadron pilots be forced to betray through their families being held hostage, always ending in Redemption Equals Death.
- In Casino Royale (2006), Vesper is revealed to be working for the bad guys because they have her boyfriend. Quantum of Solace adds an interesting twist by revealing the "boyfriend" is in fact a double agent who specializes in romancing women and then faking his capture in order to ensure their cooperation. He's trying this on a Canadian agent when Bond catches up to him.
- Red Dawn (1984) features a literal implementation of the trope: the Wolverines are betrayed by one of their own after the Commies threaten his father. Subverted somewhat in that it doesn't work as a "Get out of Jail Free" Card as far as the other kids are concerned (what with most of their parents having been killed by the Commies already).
- Notably defied in every alternate ending to Clue. "Communism was just a Red Herring." Get it? "Red"?
- Ian Fleming did it in Casino Royale.
- In Dune the character Wellington Yueh has a wife captured by the Harkonnen. For this reason he betrays the Atreides (his loyalty conditioning would make this otherwise impossible, but I guess his loyalty to his wife is able to trump even that).
- As a bit of a subversion, they'll only kill Yueh's wife if he does go along with it. Otherwise, she's stuck in permanent torture.
- In The Scarlet Pimpernel, Lady Marguerite Blakeney is an intelligent, beautiful, sophisticated yet naive young woman who is unhappy in her marriage. She betrays Scarlet Pimpernel to the evil Citizen Chauvelin because Chauvelin has dirt on her brother. Of course, her foppish husband, who she really does love after all, is the Scarlet Pimpernel]]. And she didn't actually betray the Pimpernel's identity, just his plans. Which Percy was prepared for. And she told him about it, albeit indirectly. And once she figured out what was going on with Percy, she hightailed it to France to try and help. Marguerite didn't just have Armand's difficulty to get her out of trouble.
- In James Swallow's Warhammer 40,000 novel Faith & Fire, the psyker Vaun escapes by convincing some crew members that his cell really holds someone they love. One, being interrogated, weeps about his beautiful daughter, and the prison warden says he has no daughter. On being asked what his daughter's name is, he dies.
- Later in the Harry Potter series, the Malfoy family. In Deathly Hallows, Narcissa Malfoy falsely announces to the Death Eaters that Harry is dead in exchange for knowing that Draco is still alive.
- Xenophilius Lovegood betrays Harry and his friends because his daughter Luna was kidnapped by the Death Eaters.
- Many people claim this anyway in Harry Potter when Voldemort is in power. Plenty are genuinely being blackmailed, or coerced into doing terrible things by Voldemort threatening their families, but others claim this when they worked for him willingly.
- The Memory, Sorrow and Thorn series uses this trope once in the battle of the Stone of Farewell. The former mayor of some of the townfolk who follow Josua agrees to lead Duke Fengbald, leader of the enemy army, and his elite troops, to a weakly defended "back door" because his daughters are being held hostage. The trope is subverted when he leads Fengbald into a trap instead, being willing to sacrifice his own life and those of the hostages in order to defeat the enemy.
- In the Lord Darcy story Too Many Magicians, Ewen McAllister was blackmailing Tia Einzig by claiming that Polish Intelligence was holding her uncle hostage. His plans get derailed when she learns that not only is her uncle not being held prisoner, the Poles weren't even aware of the fact that he wasn't dead.
- In the Paladin of Shadows book Unto the Breach, Dr. Arensky was forced into working for the villains because his daughter was taken by them.
- The end of Empire of Ivory this trope comes up when, as he is about to hand himself over to the British after foiling the Admiralty's plot to unleash a lethal epidemic upon the dragons of the continent, Laurence makes a last ditch plea for Temeraire not to join him. Temeraire in turn asks if Laurence would claim he was carried off against his will and forced into his "crimes" by the big scary dragon if he did so, correctly predicting his response to the idea of trying to save his skin with such lies and slander.
- MacGyver (1985), frequently. The first instance is in the episode "Deathlock".
- This was used several times as a plot device in Hogan's Heroes, requiring the Heroes to rescue the daughter/father/what have you of the blackmailed individual.
- 24, a lot.
- Subverted in NCIS. Agent Lee is revealed to be the traitor because her sister/daughter (long story) was in trouble. Redemption Equals Death in this case, but it's unlikely that the traitor would have faced anything less than a long stay in federal prison.
- In the Doctor Who new-series-three finale, Martha actually relies on a woman whose son has been imprisoned to betray her as part of a Batman Gambit. After the events of the entire year have been reversed, she goes and finds that woman (who has now never met her), gives her a flower and tells her there are no hard feelings. (In the DVD Commentary the cast argue over how much sympathy the character should get.)
- In the 1940's Wonder Woman series, a villainness Paula von Gunther who worked for the Nazis was revealed as doing so because they had her daughter captive. (In the comics she was a willing accomplice, until her HeelFace Turn.)
- In the season 1 finale of Agents of S.H.I.E.L.D. we learn that most people working for HYDRA are there because of the "incentive plan" - namely, keeping loved ones hostage to make people work on their behalf. This extends to kidnapping other people's loved ones and making them work for the bad guys too.
- In an episode of Star Trek: Deep Space Nine, O'Brien's wife Keiko is possessed by a Pah Wraith that threatens to kill her unless O'Brien helps it with some bizarre scheme. O'Brien reluctantly goes along with it until he figures out exactly what the Wraith's plan is. It wanted to use the station's equipment to kill the Prophets. O'Brien changes things so the energy zap intended for the wormhole instead hits their runabout, killing the Wraith and freeing Keiko.
- Olga Gurlukovitch turns out to be working for the Patriots because they kidnapped her newborn daughter, Sunny. This serves as a Kick the Dog moment for The Omniscient Council of Vagueness. Especially with The Reveal that she has a bomb implanted in her which is set to go off if Raiden dies. Who needs a "I have faith in you" motivational speech when you got "Screw up and an innocent child will die with you"?
- In Tales of the Abyss it is revealed that Anise betrayed the party and spied on them for Mohs because he has her parents.
- For once, Dr. Wily did it to a Commie. Dr. Cossack in Mega Man 4.
- Teen Titans: Robin is for a while forced to do anything the Big Bad Slade says, else he'll activate the lethal nanobots in the rest of the Titans.
- In Exo Squad, Diana's spouse and son being held in a Neosapien stalag on Venus justifies the betrayal of La Résistance. A HeelFace Turn comes when she learns that Neosapien prisoners "sent to Venus" are killed on route.
- Parodied in the Indiana Jones episode of Phineas and Ferb when Isabella betrays the boys to Doofenshmirtz in order to get back her mother. This being Phineas and Ferb, she has a business card that says "Dirty Double-Crosser".