Jesse and Celine, a couple who met nine years ago, now live in Greece with their twin daughters. Jesse struggles to maintain a relationship with his son while Celine considers a job in government. As they drop Jesse's son off at the airport, tensions arise, leaving Jesse feeling confused. They then drive home together, revealing they have twin daughters.

A young man and woman meet on a train in Europe and spend one night together in Vienna. They roam around the city, talking openly about love, life, and religion. They feel a romantic connection and share a passionate kiss at sunset. They admit their attraction but know they won't see each other again. Before parting, they agree to meet in six months at the same place.

Nine years after their first meeting, Jesse and Celine encounter each other again on Jesse's book tour in Paris. As they navigate the city, they reveal their dissatisfactions with their lives and slowly rekindle their old feelings. The movie explores themes of connection, regret, and the enduring power of a single night spent together.