In-ku is a pharmacist who runs his own store in Seoul. Although approaching middle age, he still lives with his elderly mother and mentally disabled older brother, In-seob. In-ku spends much of his time caring for his brother, and in the recent past had to end a relationship with his girlfriend, as her parents would not accept In-seob into their family. Hye-ran earns a living by selling fake designer clothes on a stall in Seoul's Dongdaemun shopping mall, a practise which has led to trouble with the police on several occasions. She is also saddled with a crippling debt, inherited from her now-deceased father.

While Hye-ran enjoys a night out with her family at a karaoke box, her younger sister announces that she is pregnant and wants to get married. Fearing that she will be left to pay their debt by herself, Hye-ran upsets her sister by telling her to wait and get an abortion. Meanwhile, In-ku gets a surprise visit from his ex-girlfriend, who wants to see him one last time before she marries another man. After sharing a meal they go to a hotel for sex, but once there he has second thoughts and walks away. Back at his shop, In-ku sits and drinks a beer by himself, when Hye-ran comes in looking for something to help her sleep. One thing leads to another, and they end up getting drunk at a local bar, before ending up back at the same hotel where they spend the night together. In the early hours of the following morning, Hye-ran sneaks away without saying a word, while In-ku pretends to be asleep.

In-ku and Hye-ran keep running into each other, gradually building up a friendship. They arrange a date, but when In-ku goes to meet her at work he arrives just in time to see her being taken away by the police, her stall having been raided again. At home, In-ku gets angry with his brother who has been throwing hysterics, though they later make up. Recognising the sexual needs of his older brother, In-ku arranges for In-seob to meet a prostitute, but things don't work out, and the two men end up going to a sauna instead.

Eventually, In-ku and Hye-ran manage to go on a proper date together, and after walking her home at the end of the night he surprises her with a kiss. Now spending time together as a couple, In-ku takes Hye-ran camping by a lakeside. As they talk, Hye-ran tells him about a song that used to get played at her elementary school at the end of each day, and how she wonders if they still play it. In-ku reminisces about In-seob in his younger days before he became ill, and how he used to enjoy hiking. The next day, In-ku decides to take Hye-ran to her old school, but their time is cut short when she gets a phone call and rushes off to meet her sister. Sometime later, Hye-ran meets In-ku at his shop; she feels guilty about being happy when she has so many problems, and decides to end their relationship.

As In-ku prepares for the death anniversary of his father, In-seob becomes hysterical again and runs off. In-ku goes out to look for him and tells his mother to stay at home, but feeling distraught she goes out anyway, and in a panic she runs into the road where she is struck by an oncoming car and killed. After the funeral, In-ku meets with Hye-ran for a heart to heart conversation. He admits to sometimes feeling resentful towards In-seob, but acknowledges that he is the only one left who can look after him. Sometime later, In-ku goes hiking with In-seob, sending photos of their journey to Hye-ran. Hye-ran finally visits her old elementary school, and, elated to find that they still play the song she remembers from her childhood, leaves a message on In-ku's answering machine.