A married couple and the wife's younger brother live together. The wife not only has a physical relationship with her husband, but also with her brother, with her husband's approval. This film follows their unusual daily lives, with the couple having sex at night, and the siblings having sex after the husband goes to work. The three know that the other siblings have sex separately, but there is an unspoken rule that they never look at each other. With each of their consent, the siblings show off their sex in front of the husband...