Eighteen-year-old Da-seul was spending an ordinary life helping her father run a traditional makgeolli (rice wine) brewery. However, because the origin of the ‘nuruk’ (the yeast) that determines the taste of the makgeolli was unknown, their makgeolli could not be officially distributed, and they ended up secretly selling it only to the local villagers. Her older brother, Da-hyeon, who wanted to modernize the brewery, secretly threw away the old nuruk and replaced it with a commercially available one without telling their father or Da-seul. He thought no one would notice—but from that day on, Da-seul fell ill as if possessed, saying “the nuruk is gone.” At first, Da-hyeon found it absurd, but as Da-seul’s condition worsened, he began to take it seriously. He eventually discovers traces of the nuruk in an unexpected place, and through a chaotic episode involving homeless people, Da-seul and Da-hyeon come to face a truth they had long turned away from. The nuruk that Da-seul was obsessed with was not just the secret to flavor, but a fixation on the past and an intangible burden held by the family. Only by fully accepting the past and letting go of that obsession can a new fermentation truly begin. This leaves a lingering message. Director Jang Dongyoon, who made a strong impression with his short film Please Be My Ear presented at BIFAN 2023, returns with his first feature film The Yeast, showing his growth through a more delicate narrative and direction. Taking on both the screenplay and directing, the director uses the fresh subject of nuruk to unravel heavy themes such as family, tradition, obsession, forgiveness, and recovery. The meaning of family and self-restoration that begins to bloom in the place where the nuruk disappeared slowly ferments like nuruk itself, leaving a lasting impact on the audience. (Kani KIM)