The body of a 59-year-old male is found on the banks of a river. The stepson, Kazuo, confesses to his involvement but also implicates his estranged sister Nami. Two detectives, Okishima Keisuke and Kono Kaoru, then travel to the resort district of Beppu to stake out the house of Nami's ex-lover. They feel he may also be implicated in the murder and are certain that Nami will make contact. The detectives now wait.