October 28, 1940. Along with the Italian army's attack on the Greek-Albanian border, Greece comes under fire from the Italian air force. The submarine Papanikolis, commanded by Captain Milto Iatridis and First Officer Vasilis Aslanoglou, is ordered to patrol the Gulf of Patras. Following the army's victories, the war council decides that it is time for the navy to enter the war and orders the submarine Papanikolis to patrol the Strait of Otranto. There, the crew captures the crew of an Italian ship and their engineer reveals the minefields of the Adriatic. Thus, the Papanikolis begins its mission. After completing its mission, it returns to its base, where it is honored.