Six-year-old Su-a, who is confined to room 302, is mentally retarded by abuse and does not cry. Su-a, with an iron cord around her waist, went out and waited for her mother Da-young, who didn't return for more than 10 days. She is dying of hunger. Soon-im bought her granddaughter's birthday clothes that evening and went to the studio building, I hear from Jeong-min, who lives next door, that Da-young has not returned home for 15 days. Soon-im, who lost his reason, broke the door with the help of Jeong-min and laid down coldly on Su-a's chest Weep in our arms. The order is that Da-young, who came to the hospital with the police, has no choice but to give Su-a back helplessly. Soon-im, who makes the last decision to save her only granddaughter, kidnaps Da-young with the help of Jeong-min, Soon-im, who drags Da-young, who is chained, and struggles to climb the mountain, enters the dark cave together.