What term indicates a sudden change in the direction of a narrative?

The correct term for a sudden change in the direction of a narrative is peripety. Peripety, which is derived from Greek drama, refers to a turning point in a story where the protagonist experiences a reversal of fortune or a significant change in circumstance. This pivotal moment can alter the trajectory of the narrative, often leading to unexpected outcomes that can redefine the plot and characters' motivations.

Climax, while related, specifically denotes the peak of tension or conflict in the story, which may not necessarily involve a sudden change in direction. A twist, although it suggests an unexpected turn, can be broader and does not specifically imply a reversal of fate. Crescendo refers to a gradual increase in volume or intensity, commonly used in music rather than narrative structure, and does not relate to a shift in plot direction.