Jesse (ETHAN HAWKE) is an author promoting his latest work in Paris that's based on his real-life, one-day encounter with the woman of his dreams in Vienna. He's about to fly back to the U.S. when that very woman, Celine (JULIE DELPY), suddenly shows up at his book signing, stating that she saw advertisements for his appearance and had to stop by.
The two immediately take up where they left off some nine years earlier, first discussing why their subsequently planned meeting never happened and then catching up on what's happened to them since then.
With only a few hours before his flight, Jesse and Celine wander the streets of Paris as they reconnect, explore their feelings about themselves and each other, and ponder what might have been between them.