It is told simply, and it is based on fact. On May 22, 1963, Gregorios Lambrakis was fatally injured in a "traffic accident." He was a deputy of the opposition party in Greece. The accident theory smelled, and the government appointed an investigator to look into the affair.

His tacit duty was to reaffirm the official version of the death, but his investigation convinced him that Lambrakis had, indeed, been assassinated by a clandestine right-wing organization. High-ranking army and police officials were implicated. The plot was unmasked in court and sentences were handed down -- stiff sentences to the little guys (dupes, really) who had carried out the murder, and acquittal for the influential officials who had ordered it.

But the story was not over. When the Army junta staged its coup in 1967, the right-wing generals and the police chief were cleared of all charges and "rehabilitated." Those responsible for unmasking the assassination now became political criminals.

These would seem to be completely political events, but the young director Costa-Gravas has told them in a style that is almost unbearably exciting. "Z" is at the same time a political cry of rage and a brilliant suspense thriller. It even ends in a chase: Not through the streets but through a maze of facts, alibis and official corruption.

Like Gillo Pontecorvo, who directed "Battle of Algiers," Costa-Gravas maintains a point of view above the level of the events he photographs. His protagonist changes during the film as he leads us from an initial personal involvement to the indictment of an entire political system. At first, we are interested in Yves Montand, the wise and gentle political leader who is slain. Then our attention is directed to the widow (Irene Papas) and to the opposition leaders who will carry on (Charles Denner and Bernard Fresson).