Until September is a 1984 romantic drama directed by Richard Marquand. The film is set in 1980s Paris, France. Until September follows the lives of married Parisian Xavier de la Perouse (Thierry Lhermitte) and vacationing American Mo Alexander (Karen Allen). The film begins with Mo missing her flight back to America following a trip to France with a tour group. She sullenly returns to her hotel in Paris, where she meets Xavier. She knows he is married, but he still pursues her, and Mo quickly gives in to the short term fling that ensues. To Xavier, Mo represents an opportunity for him to have some fun while his family is away, with no fear of consequences, as Mo will soon be returning to her own country. However, he discovers that the relationship may not be as simple as he once thought. Both characters undergo a great deal of personal reflection as they consider the moral implications of their actions.