The true story of the underwater action “Papanikolis” during the Greek-Italian war 1940-41. The submarine “Papanikolis”, with Commander Miltos Iatridis and the second mate Vasilis Aslanoglou, is commanded to patrol the Patraikos gulf. Following the victories of the army, the war council decides that it is time for the navy to enter the war and order the submarine Papanikolis to patrol in the narrow streets of Otranto.