In a plot, the point of greatest tension or turning point is called the climax. It is the moment when the central conflict reaches its most intense stage and the protagonist faces the decisive challenge.
The climax usually follows the rising action, during which complications and stakes increase. After the climax, the story moves toward falling action and resolution, where the consequences of the decisive event are revealed and major conflicts are settled.
The exact location of a climax can vary by genre and narrative structure. In some stories it is a confrontation, revelation, choice, or reversal rather than an action sequence. A mystery may place its climax in the unmasking of the culprit; an adventure may use a final battle; a tragedy may centre on an irreversible decision.
Exposition introduces the setting and characters, while denouement and resolution describe what happens after the central crisis. Those terms are related to plot structure, but they do not name the point of highest tension itself.