In the film, "Mother" and her son Yuan Bin are constantly discriminated against (the son is indifferent to his mother's concern for him), the living space is already deformed, and the son Yuan Bin was imprisoned again because of injustice. After the son was released from prison, he had dinner with his mother. The son told his mother his guess about why the murderer dragged the body to the rooftop, in order for everyone to find out as soon as possible and provide rescue. This is the pure logic of mentally handicapped children. The mother's face was very ugly, because the son could think of this and it might not be far from recalling the murder process, and the arrival of that moment would have devastating consequences for this family who could no longer bear the "true memories". At the end, the son gave the acupuncture box to the mother. The mother is a healthy person, but the memory is constantly tormenting her. In order to continue to survive, she longs to forget, including poisoning her son and killing the old man. The son is mentally handicapped, he longs for complete memories, so he desperately tries to recall them, but he can't predict whether these memories are good or not, and putting a needle into the acupuncture point in his thigh will forget the bad memories, so the mother chose him in the end