九年前，杰西（伊桑·霍克 Ethan Hawke 饰）与席琳（朱莉·德尔佩 Julie Delpy 饰）在火车上不期而遇，怦然心动。在维也纳渡过疯狂而又浪漫的一夜后，他们在日出前分手，并相约在维也纳重逢。 　　九年之后，杰西已成为畅销书作家，而席琳则是法国环保组织成员。杰西在新书里娓娓道来的，正是九年前的浪漫夜晚。在巴黎促销新书时，杰西与席琳在书店相遇，然而他们只有一下午的时光相处，日落之前，杰西要乘飞机赶回美国。两人在午后的巴黎街头散步，在美丽的护城河上泛舟，无所不谈，兴致勃勃。可是就像命运的捉弄，快乐的时光像烟花一样醉人却短暂。 　　杰西对席琳一送再送，难以忘情；席琳用吉他和歌声，怀念着内心深处的爱恋。太阳就快落下去了，杰西就要误了飞机，又或许他更不想错过的，是命里注定的缘分。Early thirty-something American Jesse Wallace is in a Paris bookstore, the last stop on a tour to promote his best selling book, This Time. Although he is vague to reporters about the source material for the book, it is about his chance encounter nine years earlier on June 15-16, 1994 with a Parisienne named Celine, and the memorable and romantic day and evening they spent together in Vienna. At the end of their encounter at the Vienna train station, which is also how the book ends, they, not providing contact information to the other, vowed to meet each other again in exactly six months at that very spot. As the media scrum at the bookstore nears its conclusion, Jesse spots Celine in the crowd, she who only found out about the book when she earlier saw his photograph promoting this public appearance. Much like their previous encounter, Jesse and Celine, who is now an environmental activist, decide to spend time together until he is supposed to catch his flight back to New York, this time only being about an hour. Beyond the issue of the six month meeting, what has happened in their lives in the intervening nine years, and their current lives, they once again talk about their philosophies of life and love, this time with the knowledge of their day together and how it shaped what has happened to them.