Longtime friends Seong-ji and Ji-won are excited to begin university in Seoul, swearing to stay close in the big city, but from the moment they arrive, they begin to drift apart.

Her focus split between her rigorous accounting program and her overnight job at a grocery store, Seong-ji tries to make peace with the loss. It's during her overnight shifts that she encounters an enigmatic young woman who spends her nights entering the empty homes of other people to paint and photograph these places. Now, the normally rational Seong-ji finds herself swept up in a dreamlike otherworld, made up of freedom and creativity. As she explores these quiet places, she uncovers not only an intimate portrait of strangers, but perhaps even herself.

But as the nocturnal walks reveal the possibilities of the future, they also force her to relive the pain of her lost friendship with Ji-won...