Fratelli d'Italia plot
Capodistria, 1915: Nazario Sauro, Captain in the Commercial Navy of Austria, flees to escape his arrest and takes refuge in Venice. When Italy declares war on the Austro-Hungarian Monarchy, Sauro enlists in the Royal Navy aboard the submarine "G. Pullino". His perfect knowledge of the coast offers him the opportunity to provide a remarkable service to his homeland. The "Pullino" sails very close to an Austrian base. The exploration is a complete success but costs the life of Sergio, a devoted sailor whom Sauro has great support. But on its return, the submarine runs aground and the crew is captured.