Top Secret - The Hermes Case (1967)

Original title: Άκρως απόρρητον - Υπόθεσις Ερμής

A series of mysterious murders is causing headaches for the country's secret services, who are discreetly but persistently investigating every aspect of the case. With the help of various coincidences, it is revealed that the crimes are linked to the activities of foreign agents operating in Greece. As it turns out, all these agents—although their origin is not specified—are trying to steal a series of valuable and highly classified documents related to some "serious" experiments being carried out secretly at a NATO military base. Espionage against espionage and constant chases.