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 [...] [tvtropes.org]