Syphax and Massinissa, princes of Libya, are rivals for the hand of Sophonisba, daughter of Asdrubal, a powerful Carthaginian nobleman. Massinissa's suit is accepted; whereupon Syphax enters into a league with Scipio, who is advancing against Carthage. On Sophonisba's marriage-night news is brought that the Carthaginian forces stationed at Utica have been defeated by the united armies of Scipio and Syphax. Massinissa is ordered by the senate to march without delay against the enemy; he loyally obeys the command, and takes leave of his virgin-wife. While he is serving Carthage in the field, the Carthaginian senators at home proceed to plot against his life. They determine to gain Syphax to their side by giving him Sophonisba to wife; and Gisco, a physician and skilful empoisoner, is sent to the Carthaginian camp to despatch Massinissa. Among the senators there is an honest old man, Gelosso, who disguises himself, follows Gisco to the camp, and hands Massinissa a letter containing a disclosure of the plot. Massinissa has no sooner dismissed the empoisoner (whom he scorns to punish) than Jugurth, Massinissa's nephew, enters, to announce that Syphax has been seen riding in the direction of Cirta, and that his horsemen are coming at a leisurely pace towards the camp as if to fraternise with Massinissa's forces. By advice of Gelosso, who lays aside his disguise, Massinissa scatters the horsemen by a sudden onslaught, and hastens to make a league with Scipio. Meanwhile Sophonisba has been sent by the Carthaginian senators to the palace of Syphax at Cirta. She escapes by a subterranean passage that led from the palace to a forest, but through the treachery of her attendant, Zanthia, falls again into the hands of Syphax. In despair of effecting his purpose by persuasion, Syphax applies for help to a powerful enchantress, Erictho, who engages to force Sophonisba by magic to his arms, on condition that he shall speak no word, and have no lights burning, while he embraces her. On the appointed night Syphax discovers to his horror that his embraces have been given to Erictho. While he is cursing his fortunes, a messenger arrives to announce that Scipio and Massinissa are advancing against Cirta. He marches out to meet them; the troops on either side withdraw, while Syphax and Massinissa engage in single combat; Massinissa vanquishes his opponent, but spares his life on receiving assurance that Sophonisba has not suffered outrage. Leaving his prisoner in Scipio's hands, Massinissa hastens to Cirta. He enters the palace with his beaver down, unrecognised by Sophonisba, who throws herself at his feet, and implores him to save her from falling into the hands of the Romans, or grant her instant death. Pledging his oath that he will protect her, he doffs his helmet. The joyful reunion is presently interrupted by the entrance of the Roman general, Lælius, who orders Massinissa to deliver Sophonisba into Scipio's custody (Syphax having