College student Junichi Satoshino (played by Takashi Godai) is determined to break into high society, so he takes a holiday job at a high-end restaurant in Karuizawa. A few days later, he is assigned as a waiter to the villa of the president of Nakagawa Corporation, Genichiro Nakagawa (played by Yoshio Tsuchiya). There, he falls in love with the president's wife, Yoshiko (played by Miwa Takada). In a daze, Junichi accidentally drops a plate and is harshly reprimanded by Nakagawa, but Yoshiko defends him. The next day, after being fired, Junichi unexpectedly encounters Yoshiko, who is with her son, Yuichi (played by Masato Ito). Yoshiko has left her wealthy lover Nakagawa and is living a lonely life. She expresses sympathy for Junichi's predicament and decides to hire him as a tutor. Junichi seizes the opportunity to advance and successfully seduces Yoshiko. However, after moving into the villa of Yoshiko's deceased sister, Yoshiko's niece Aya (played by Yumi Yoshikawa) and her boyfriend, the heir of the Okazaki conglomerate, Yasuhiro (played by Takashi Godai), target Junichi. Yasuhiro, having a criminal record, wants to use Junichi to fabricate his own death to escape the police and his enemies. One night, Junichi and Aya go to the Okazaki villa as planned and discover Yasuhiro's corpse, which has been dead for quite some time. Fearing being implicated, Junichi hurriedly buries the body and threatens Aya, claiming they are co-conspirators, forcing her to marry him. When Junichi and Aya go out to dinner, they run into Yoshiko with Yuichi. Upon learning that the two are engaged, a devastated Yoshiko silently leaves the restaurant. Seeing Yoshiko in such despair, Junichi can't help but confess the truth to her. To confirm the truth, Yoshiko reports to the police, which leads to the discovery of Yasuhiro's body. Junichi and Aya are forced to flee in a car but end up colliding with a speeding train, resulting in their deaths on the spot. Upon hearing of Junichi's death, Yoshiko goes to the morgue. There, Inspector Hisajima (played by Shinjiro Kawai) informs her that it was not Junichi who killed Yasuhiro. Yoshiko kisses Junichi, whose throat has been cut, feeling a mix of emotions. The summer in Karuizawa is coming to an end, as if nothing ever happened...
