In the town of Pompeii, 79AD, a few weeks before the volcanic eruption of Vesuvius, a Roman lady Hélène meets and falls in love with a young Greek man Lysias. He is betrothed to another woman who, to win him back, acquires a potion to make him love only her. The potion was prepared by the Egyptian priest, Arbax, who has a grudge against Lysias, and is not what it seems, it is intended to drive whoever takes it insane. Hélène's new slave is also in love with Lysias. She steals the potion and gives it to Lysias, who hurries away in a mad rage. When the slave girl confronts Arbax, she is killed by the evil priest, and Lysias is charged with her murder.