影片改编自塩田武士的同名推理小说,以昭和年间最大的未解决事件为主题,讲述新闻记者阿久津英士(小栗旬饰)和少年时期与该事件有关联的男人曾根俊也(星野源)之间的故事。A newspaper reporter is working on an investigative piece regarding an unsolved mystery dating back thirty years. there was gangsterism and extortion at play. As part of his work the man comes across a riddle of a cassette tape. Alsmost at the same time a man in Kyoto comes across a cassette among his father's belongings. He hears himself.