In the prologue, the goddesses Fortuna and Virtu are unable to contradict the goddess Amore’s claim of having the most power over mankind, and submit to her control over history.

Rome during Nerone’s rule. (Early Morning). Ottone, recently returned from war, looks forward to a reunion with his lover, Poppea, until he notices two imperial guards outside her house; this incident forces him to realize that Poppea must have taken Nerone, the Emperor himself, as her lover. Accusing Poppea of being both false and fickle, he departs in despair. The two guards awaken and curse love, Poppea and Nerone, the state of Rome and all military duties, agreeing that they can trust no one.

Poppea and Nerone enter as Poppea begs him not to leave her in this present state – one of nervousness and desire to caress and embrace him. Nerone says he must do so since he has not yet renounced his wife, the Empress Ottavia; however, he vows to return as soon as possible and confirm his love for Poppea, saying that wherever he goes, she will be with him in memory as one of shining beauty. Poppea’s nurse Arnalta warns her of Nerone’s reputation and reminds her that very often great men will desert those to whom they are professing love and leave them in shame and scandal. However, Poppea’s ambition remains steadfast and she expresses her lack of fear over whatever events shall occur.

Ottavia exclaims her title as Empress and laments over being dishonored as the consort of Nerone while desperately begging the gods to take vengeance on Nerone. She immediately repents of this blasphemy, swearing to bear her pain and anguish in silence. Her nurse advises her to seek revenge by taking her own lover. Ottavia rejects this suggestion, saying that she would punish her own sins if the gods did not. Her nurse reiterates that she must grasp the demands and duties of high and noble vengeance. A page brings the philosopher Seneca to Ottavia; he advises her to bear her misfortune with dignity and restraint, encouraging her to allow constant virtue to strengthen her noble purpose. Ottavia ignores the advice from Seneca claiming his words are empty, artificial and hollow, and that they offer little comfort to her human sorrow. Seneca is forewarned of his death by the goddess Athena, but he says he will welcome this end as an entrance to a place of more splendid enlightenment after suffering the treacheries of these earthly days.

Nerone explains his decision to Seneca of renouncing Ottavia in order to marry Poppea. Seneca encourages him not to follow the voice of emotion but to let nobler thoughts guide his actions and to honor his wife’s feelings. Nerone furiously rebukes him claiming that in this world he reigns all powerful and that reason should not guide his actions. Their argument continues but Nerone again announces his intentions to marry Poppea. Poppea enters and the two lovers engage in a sensual exchange proclaiming their mutual admiration for one another. Nerone repeats his claim of sharing the fortune and fate of the empire with Poppea as his Empress and reaffirms his conviction to make her his consort and lawful wife. Poppea is overjoyed at the prospect and convinces him that Seneca is trying to persuade others that his reign depends on Seneca alone. Having been convinced of Seneca’s disloyalty, Nerone orders his execution.

Ottone and Poppea have a final confrontation. He questions why his love goes unrewarded, but Poppea rejects him saying she belongs to the Emperor. Ottone recognizes Poppea’s quest for power and, fearing that he will be destroyed if she reaches her goal, resolves to thwart her attempt. Arnalta has overheard their conversation and expresses her sympathy for Ottone and reveals her feelings that Poppea has lost her senses. Ottone now turns to Drusilla, his former lover, for solace and consolation.

Ottavia’s page Valletto has a flirtation with one of her ladies-in­waiting, Damigella. The page is discovering his sexuality and every woman in the palace is a likely candidate. Damigella is all too astute in such matters and promises him his desires if he will consent to a loving relationship.

Seneca receives the death sentence and bids a dignified farewell to his friends.

Nerone celebrates the death of Seneca with Lucano in songs of praise to Poppea.

Ottavia persuades Ottone to kill Poppea, and he borrows some of Drusilla’s clothes as a disguise. Drusilla happily agrees to help him in every way, but asks why he must commit this terrible deed.

Poppea talks to Arnalta in her garden of her excitement about her impending wedding, and promises to keep Arnalta as her confidante when she is Empress. Arnalta sings Poppea to sleep with a lullaby. Ottone enters the garden disguised in Drusilla’s clothes, but the goddess Amore protects Poppea from the murder attempt. Drusilla is naturally suspected.

Drusilla is arrested and, despite her protestations of innocence, is about to be executed when Ottone discloses his guilt and Ottavia’s plot. The Emperor orders his banishment and Drusilla announces that she will share his exile happily. Nerone banishes Ottavia immediately from Rome to drift at sea in a wooden boat.

Poppea learns of the plot and rejoices that Nerone finally has a reason to repudiate Ottavia and fulfill his vow to make Poppea Empress of Rome. Arnalta revels in her imminent promotion from slave to sought after confidante to the new Empress.

The immortals grant Amore her claim as the most powerful, and she elevates Poppea to the rank of goddess. Nerone and Poppea exultantly celebrate the power of love at Poppea’s coronation.