In Mystery Fiction
, especially in "Cozy" settings, we usually have a cast of characters of upper or uppper-middle class, and a crime against one of them, often the richest: a murdered millionaire, or a stolen gem from a Duchess. All the main characters, and the detectives as well, generally support the existing social order. This trope applies when one of the characters makes himself (or herself, but usually it's a man) suspicious by having radical political views, such as Communism or Anarchism. After all (the other characters think), if this guy supports a proletarian revolution lynching the plutocrats, why wouldn't he murder the millionaire? If he thinks property is theft, why not relieve the Duchess of her property?
This is invariably a Red Herring
, and the true crime was commited for conventional "private" motives (probably greed, in the examples used), with nothing political behind it.
- Two from Chesterton's Father Brown stories: In "The Flying Stars", a journalist with socialist leanings is suspected of stealing diamonds. In "The Crime of the Communist", a Communist professor is suspected of murdering three millionaires. In both cases they are innocent.
- Also two from Agatha Christie. In "Death on the Nile", one of the suspects of murdering the rich heiress is a young man with radical left-wing views. In "One, Two, Buckle My Shoe" there are two suspects with radical idieologies, one of them left-wing, the other one right-wing. All of them are red herrings.