A world-class hitman ends up swapping identities with a down-to-luck extra actor during an accident.

The film tells the story of a retired father who comes to the park's dating corner to find a marriage partner for his son, but inadvertently gets involved in an emotional whirlpool.

One day, Lan Xia goes to her classmate Hai Feng’s house to stay overnight. They start to feel awkward around each other without really knowing why, but slowly get closer through insignificant words exchanged while doing a jigsaw puzzle of the world map. The next morning, Hai Feng realizes that Lan Xia has left without saying anything and sets out to follow her. A memory of a summer in which the world belonged to the two of them alone, if only for a moment