The denouement is the last movement of a story or a play, when the plot’s remaining questions are answered and the mess is sorted. Learner books often call it “the exciting last part,” which is close enough for a first meeting — though actually, the most exciting peak is often the climax, and the denouement comes after, when secrets come out and threads are tied up. It can be quiet, even sad; it does not have to bang. English took the word from French, and careful writers sometimes still spell it dénouement. The old picture is an untying: the story was a knot, and now the knot comes undone. You will meet it in literature class and in reviews, not in everyday chat about a film, where people just say “the ending.”