Also known as 3-act structure · three acts
A common story shape: setup (Act One), confrontation (Act Two), and resolution (Act Three), with major turns at the act breaks that re-aim the protagonist's goal and cost.
Act One establishes world, want, and the inciting incident that makes the old life impossible. By the first act break, the protagonist should enter a new problem space with a clear pursuit. If Act One only tours tone without a decision that costs something, Act Two has nothing solid to complicate for the next hundred pages.
Act Two is escalation and reversals, not a flat middle of tasks. The midpoint should redefine the goal or the cost so the second half is not a repeat of the first. B-stories and character arcs braid here; if they never pressure the A-plot want, they read as side quests the audience can skip without feeling the loss.
Act Three forces a final confrontation and a changed world -- victory, failure, or a costly mix. Three-act language is a map, not a prison: TV may split acts for commercials, and some forms use five acts. Use the model to test whether pressure rises; do not force empty "Act IIb" labels that do not change tactics on the page.
Many do in broad shape, but it is a diagnostic map, not a law. Some stories use four or five movements; the test is rising pressure, not matching a template brand.
Roughly around the middle of Act Two -- a turn that redefines the goal, the stakes, or what the protagonist believes is true.
Episodes often use act breaks for format and commercials, plus a series engine. Still ask whether each movement re-aims want and cost.
A beat sheet names the turns inside the acts -- inciting incident, midpoint, climax -- so you can test the spine before drafting every scene.
