Asako Mizusawa is a fifty-year-old homemaker. She endured her mother-in-law's sarcasm and passive aggressive moves when her husband, Hiroyuki, decided to move in with his parents. And while she regained her freedom when her mother-in-law passed away, a life-changing event takes place two years later. It happens when her son Yuta marries a woman named Ririka. Asako has now become the mother-in-law! Asako did not approve of the marriage, but she was willing to accept it under one condition that they all live together under the same roof. Unexpectedly, Ririka agreed with a smile. Ririka invites Asako to share a bottle of wine on the first day they move in. They have a lively conversation about marital problems and Asako even mentions an affair her husband has had in the past. The two appear to be getting along, but it is all a ploy by Ririko to learn more about Asako...

From the next day on, Asako notices Ririka doing suspicious things. Wanting to know more, she begins to snoop around. She learns that Ririka used to work at a bar and was more than friendly with her customers. Asako becomes determined to make her son see who Ririka really is, but her attempts only work to alienate herself from her son and her husband also takes Ririka's side. Meanwhile, a man in the neighborhood disappears. Detectives investigating the disappearance find that the evidence leads towards Ririka...