In an attempt to stem the heroin trade from Iran, a group of narcotics agents working for the UN inject a radioactive compound into a seized shipment of opium, in the hopes that it will lead them to the main heroin distributor in Europe. Along the way, they encounter a mysterious woman doing her own investigating of the smuggling operation.

Repression is the rule of the day in this film that skewers Greek governance of the 1960s. Z, a leftist rabble rouser, is killed in what appears to be a traffic accident. But given the political climate, the death of such a prominent activist raises troubling questions. Though it’s too late to save Z’s life, a postmortem examination suggests that the ruling party was behind his death. As the facts leak out, those who tell the truth pay the price for their honesty.