A DARK TURN: the moment when the hero or detective finds themselves so deep into the mystery that their own rules, morals, and/or ethics are compromised. The hero must do something (usually in the second half of the novel) that somehow breaks the rules or threatens their integrity or even their innocence. These are the harrowing stakes of a good mystery. And the dark turn is why readers care about this particular case. Because the pull of this secret has become so strong, even the straightest arrows are helpless against it.
