Night is the time when everyone is in deep sleep, but for the brothers-in-law in the movie, it is different. It is the right time to spy on and secretly do lewd things with their sisters-in-law, who look extremely attractive during the day. The sisters are also not easy to deal with. When they see their brother-in-law's giant penis, they do not resist or scream, but instead cooperate and even show joy when having sex with him.