Youngdo’s father, a notorious serial killer, was executed. Youngdo wants to let go of what he remembers about his father but he doesn’t know how to do so, and he ends up releasing his anger through violence.Shot in Busan, Shadow Island is the name of a location as well as the main character's name. The film explains the legacy of violence passed down through three generations. The lives of a murderous father, a son addicted to violence, and the victims of violence intertwine into a surprising finale. As the film shifts through the past and present, it reveals a painful family history that eats away the soul and leads to a burdened fate of self-destruction.