David O. Russell’s latest venture with the returning cast of Jennifer Lawrence, Robert De Niro, and Bradley Cooper (Silver Linings Playbook) opens with the title card, “Inspired by the true stories of daring women. One in particular.” The film tells the story of Joy (Lawrence, up for a Best Actress Oscar), based on the real-life tale of Joy Mangano’s rise to home-shopping network success after she invented the self-wringing Miracle Mop while struggling to pay the bills as a single mother. Russell establishes a pleasantly screwball pace early on, and the narrative is entertaining for much of the film, carried along by the Lawrence’s radiant energy and De Niro’s wry comedic chops. But style ultimately trumps the movie’s fragmented substance, and after all the sassy lines, sunglasses, and sauntering are over, viewers may be left wondering what exactly the point was. Rated PG-13. 124 minutes. Violet Crown.