It's only right and proper that a murder mystery should end with the police arresting the true killer, right? That's the way it was in most classic mysteries at the time Friedrich Dürrenmatt was writing. But Dürrenmatt put this convention into question, both in his earlier novel The Judge and His Executioner and in this 1958 work. The Pledge has as its frame story a retired policeman encountering a mystery writer and telling him that he doesn't think much of the genre -- the greatest problem is that, with the author controlling events and determined to punish the evildoer, the detectives carry out their investigation like a mathematical proof, and can't be defeated by chance or by circumstances. So the policeman counters by telling the story of a killer who will never be brought to justice, though one of his colleagues pursues him obsessively. This makes for a rather painful story.