In the 1942 movie Casablanca, Algerian nightclub owner Rick, played by Humphrey Bogart, is jolted by the unexpected appearance of his lost Parisian love Ilsa. Rick must figure out how to handle this provocative coincidence.
The rest of the movie unfolds in response to this coincidence. No Coincidence, no story. Movies, said director Alfred Hitchcock, are like life with the boring parts taken out.