One summer morning an ad art director, Shunsuke Namiki (Koji Yakusho) leaves Tokyo in haste driving in the direction of a certain villa beside a quiet lake. In the villa Shunsuke and his wife, Minako (Hiroko Yakushimaru) are supposed to lodge together for a few days, together with two other couples, the Fujimas and the Sekitanis, for the benefit of their respective offspring, namely a girl and two boys. The parents aim to have their children cram intensively for admission for an elite private Junior and Senior High school, named Shugakukan. They are to employ an excellent cram school tutor, called Tsukumi (Etsushi Toyokawa), who himself graduated from Shugakukan.. The elegant- looking villa which is owned by a physician, Fujima( Akira Emoto) has been set aside for the parents. The three children and Tsukumi are to live in a rented villa . They come to their paretns?f villa for mealtimes only.
The audiences are informed at this stage that Shunsuke cannot endure sudden brightness;he seems to need sunglasses on such occasions.
Minako got remarried to Shunsuke when Maika Minako? daughter by a previous marriage was three but they are now living separately. However, Shunsuke was requested by Minako to join the lodging session, pretending that he is a good husband and father. On arriving at the villa, with Minako, Shunsuke gets a mock interview with Tsukumi: Shunsuke?fs replies disappoint his wife and Tsukumi, which irritates Minako. His remarks, attitudes and clothing are far from satisfactory. It is quite evident that Shunsuke is not interested in Shugakukan?fs educational policy at all. Moreover he seems to feel that Shugakukan is not the only possible school and that children should choose their future school by themselves.
During the interview sessions, an attractive young woman named Eriko Takashina suddenly turns up at the villa. She is a freelance photographer and works for Shunsuke at his studio. Soon after the film has started, it becomes clear to viewers that Shunsuke and Eriko are in love.
Eriko says that she has come to deliver some document to Shunsuke, thinking that he will need it for his work while staying at the villa. She soon leaves the villa, telling Shunsuke that she will stay overnight at a nearby hotel. On her way to the hotel, Eriko finds Tsukumi giving his pupils some physical training on a sports ground near the villa.. Through conversations between Tsukumi and Eriko, the film audience learn that Eriko, too, is a graduate from Shugakukan. Tsukumi points out that he can tell that from her polite way of bowing. While they are talking, the children continue their physical training.
At supper time, Shunsuke is stunned to find Eriko sitting at a table in the dining room and learns that Tsukumi has invited her to the barbeque party. Over dinner Eriko tells the three couples about her parents, saying that due to various problems they had ended up in getting divorced after having succeeded in letting Eriko enter Shugakukan . Eriko discloses that becoming exhausted with their quarreling she had quit the school before finishing her courses.
After the children and Tsukumi have left the villa to return to their own villa, Eriko whispers to Shunsuke that she will be waiting for him at the hotel lobby around ten and leaves the villa, after putting a key into Shunsuke?fs jacket pocket. Late in the evening, Shunsuke tells Minako that he has to go back to Tokyo to solve some urgent matters.
Minako seems to have got some uncanny gift of foresight; the audience is shown some fragments of scenes where something tragic might happen to Eriko.
Near Eriko?fs hotel, Shunsuke calls Eriko?fs cell phone but he just hears the recorded messages. In his car, he checks the photos in the envelopes Eriko had handed him. Having noticed Minako and Tsukumi in one of those photos, Shunsuke phones Minako that he will return the villa within about ten minutes as the urgent office business has been solved. On the phone Minako sounds rather tense.
At the villa, Shunsuke is astounded to discover Eriko dead with fatal injuries on her head on the living room floor. Then Minako confesses to Shunsuke that she hit her on the head in rage when Eriko has come back to the villa to ask her to part with Shunsuke, stressing that otherwise she would tell her relationship with Shunsuke to their daughter, Maika and the School. Shunsuke is staggered to hear her confession but tries to call police. But he is stopped by Fujima and Sekitani and is persuaded to discard her body in the lake; they insist that they do not want to damage their children?fs bright future by this murder. In dilemma, Shunsuke hesitates, but with appeals and persuasions by his wife and the other couples, Shunsuke finally pulls off the big table cloth to wrap Eriko?fs body after taking off all of her clothes. While doing this, Shunsuke is puzzled to find some mud in her finger nails, but soon forgets this.
Beside the lake Fujima tries to crush Eriko?fs face with a piece of a stone and burns the tips of her fingers using Shunsuke?fs lighter, they toss her body off the boat into the water. Then frightened by Fujima?fs sudden use of his flashlight, Shunsuke drops his lighter with his initials into the water..
Back at the villa, the couples attempt all the possible measures to delete Eriko?fs existence: They burn her clothes apart from her white raincoat. Minako decides to go to Eriko?fs hotel room to stay overnight, wearing her raincoat disguising herself as Eriko.
In due course, Shunsuke happens to open Eriko?fs special metal case with a small key which he found in her handbag. Inside the case, he finds lots of photos she has taken showing that Minako, Fijima?fs and Sekitani?fs wives give money to a Shugakukan staff man and Tsukumi.
Shunsuke now firmly believes that Tsukumi has actually killed Eriko and Minako tries to cover up for him because he is important for the children?fs education. Shunsuke mentions that to Tsukumi outside the villa. However, Tsukumi denies Shunsuke?fs surmise. Shunsuke tells the other couples what he has found out, adding that she was not killed inside the house but somewhere outside because of the mud at her finger nails.
Then who has killed Eriko? Fujima tells Shunsuke what has actually happened?c.