A locksmith helps an old man forgetting to take the key with him to unlock his door, only to find that the old man is not the owner of the house, who forgets where he lives after getting diagnosed with Alzheimer. Thereby, he decides to lock his mother at home to prevent his mother from getting lost. As a locksmith, he once witnessed a homosexual old man, who abandoned his family and died at home without anyone around. His mother, who is trapped at home, asks the security guard for help by opening the window. The locksmith comes back home to pacify his mother. He stops his work to take care of his mother and has to face up to the conflict between him and his mother. Nevertheless, his mother has forgotten that he is a homosexual.