1017 AD. The Republic of Pisa is organizing a fleet to drive out the Saracens who are infesting the Mediterranean. While the forces are away "The Gorgon," the young daughter of a Pisan nobleman who has been heroically killed, comes to be solemnly invested as the figurehead virgin who will maintain a lantern to celebrate the men's victorious return. In charge of the home guard is an ambitious young Florentine who feels deprived of the forthcoming honour and glory, and who seeks revenge by violating the sacred person of the virgin. He gains access to her well guarded quarters, but when the Gorgon falls helplessly in love with him, his desire for vengeance falls away. His plot exposed, he commits suicide rather than invoke the wrath of the Pisans. The Gorgon too takes her life by throwing herself from a high tower. Meanwhile, the victorious Pisan vessels return.