After his mother’s death, Gunwoo moves in with his stepfather, Yihyun—a man only fifteen years older, with whom he shares little more than a roof. Their relationship is distant, almost awkward, until Gunwoo notices strange marks on Yihyun’s body—too deliberate to ignore. A quiet curiosity takes root, and when he finds a vivid red rope hidden in Yihyun’s room, he realizes there’s more to this man than he ever imagined. The more he uncovers, the harder it is to look away.