"Sunday Seoul" is a film with three nonsensical episodes: THE WEREWOLF: A high school student Do-yeon who is the victim of bullying in school, is the main character of the first episode. He is not good at studying or at fighting. One day, an unexpected change happens to his body. THE VISITOR: On a pitch-black stormy night, a woman is visited by a stranger seeking shelter. The stranger eventually, is revealed as a serial killer on the run. THE YOUNG ADVENTURER: Seeking revenge for his father, a son embarks on a journey in which he encounters a young girl by chance and starts to learn martial arts.

With no clue how he came to be imprisoned, drugged and tortured for 15 years, a desperate man seeks revenge on his captors.