Titus has become emperor of Rome and wishes to marry his beloved African princess Berenice. The Roman Vitellia, who herself has her sights on the throne, is in the throes of anger. She demands that her suitor, Sextus, assassinate the emperor. Despite the deep friendship he has for Titus, the young man, blindly in thrall to Vitellia, is ready to fulfil her wishes. He buries his scruples and agrees to obey her. Annius announces that the emperor, yielding to the pressure of the Roman people, is ready to renounce the foreign princess. Vitellia orders Sextus to postpone the murder.

Sextus, pained at finding himself Vitellia’s plaything, raises some desperate objections, which the young woman, unruffled, sweeps aside. Annius, who wants to marry Servilia, Sextus’s sister, begs him to intercede with Titus in his favour. The emperor bids farewell to Berenice; the people and the Senate have forced her to leave. Deeply unhappy, Titus seeks comfort from his friends Sextus and Annius. As proof of his affection, he declares that he has chosen Servilia to be his wife. In the presence of the two dismayed young men, Titus sings of the joy he feels at bringing happiness to others and asks a despairing Annius to bear the happy tidings to the lucky bride‑to-be.

But Servilia refuses to wear the imperial ermine; not for one moment will she think of abandoning Annius, and the two lovers swear eternal fidelity. Servilia throws herself at Titus’s feet and avows that her heart belongs to Annius. Touched by her sincerity, her courage and the strength of her love, Titus yields to her wishes. Enter Vitellia, who, seeing Servilia’s joy, believes in a new betrayal by Titus. She bitterly reproaches Sextus and again urges him to accomplish her vengeance.

Resigned, sword in hand, Sextus begs for one last glance. Sure that vengeance will be hers, Vitellia is informed by Publius, Titus’s minister and strongman of Rome, that Titus has chosen her to be empress. Alas, she has just dispatched Sextus with the order to kill the emperor. The young man is about to perpetrate the deed. He wanders, veering between fury and despair. In Rome revolt is brewing. The Capitol is in flames. In the general confusion, with the determination brought on by madness, Sextus obeys Vitellia’s order. Titus is dead…  

Titus lives… The emperor has escaped the assassination attempt. Lentulus, one of the insurgents, had taken his crown and cloak to lead the uprising and, striking him, Sextus believed he had killed Titus. Overwhelmed by his feelings of guilt, Sextus confesses to Annius, who advises him to present himself before the emperor and admit to his crime. Vitellia, on the other hand, urges Sextus to flee. He promises not to betray her and to take his secret to the grave. Publius arrests Sextus. Titus cannot believe Sextus guilty. Annius comes to beg for mercy for his friend, who has been condemned to death by the Senate.

Despite his disappointment, Titus cannot make up his mind to sign the decree condemning Sextus without hearing him one last time. Sextus is brought before him. The two men hardly recognise each other. Sextus, not wishing to betray Vitellia, will not speak and bids farewell to the emperor with a broken heart. Titus cannot resign himself to sending him to his death and decides to pardon him. Annius and Servilia come to entreat Vitellia to use her power over Titus to save Sextus.

Moved by Sextus’s greatness of soul (he has not denounced her), she decides to confess the truth to the emperor and to bid farewell to life. While everyone is present and Sextus awaits execution, Vitellia admits that she is behind the plot. Titus is distraught: everyone has been leagued against him and even wanted to kill him. Is there no love and no true loyalty in life? At the cost of a great effort over himself and to set a good example, Titus grants a general pardon. His friends and enemies, the people and the Senate celebrate the emperor’s goodness. Titus remains in the background, alone.