The year is 1949, a mere four years after Japan's defeat in World War 2. The nation was under the boot of the American occupation, and the U.S. was determined to make Japan a stronghold against the threat of Communism. By contrast, powerful leftist movements were taking place throughout the country. On the morning of July 6, the head of the Japan National Railways (JNR) was found dead on the tracks, run over by a train. The incident occurred at the height of labor strife between the JNR and its giant labor union over impending mass lay-offs as ordered by the Americans.

Made in black and white, and mixing documentary and newsreel footage with its enacted drama, this film sets out to examine CIA involvement in Japanese post-war politics. The investigation of a senior official's assassination is carried out by a newspaper reporter (Tatsuya Nakadai, last seen as Akira Kurosawa's Kagemusha) and it becomes his obsession to probe, over 10 years, into the various institutions which shield the truth.

In many ways, the film's form is reminiscent of the work of Francesco Rosi in such films as Salvatore Giuliano and The Mattei Affair, and it is of additional interest that this method of exploring political issues now seems to be a world-wide phenomenon.