Nishimura Gosaku, an aspiring photographer who loves mountain scenery, meets a boy named Sada Ichiro one evening who asks to borrow train fare. For some reason, Ichiro follows Nishimura everywhere. When told to go home, Ichiro refuses, claiming he doesn't want to return because of his estranged parents. Reluctantly, Nishimura lets Ichiro stay the night. The next day, Nishimura takes photos of Ichiro by the Sumida River, and they part ways on good terms. Meanwhile, Ichiro's worried father, Shigeo and mother, Fujiko, desperately ask Ichiro's classmates and tutoring teachers for his whereabouts, but no one knows where he is. Suddenly, Shigeo receives a phone call demanding a ransom of 10 million yen.
