Act I

In Rome, the Emperor Eliogabalo returns from a campaign during which his Praetorian Guard mutinied. He celebrates his home coming by abducting a Roman lady: Eritea. Gemmira fears that Eliogabalo, whom she knows to be predatory and tyrannical, will disturb her love affair with Alessandro. The latter tells her that his intervention with the mutinous Guard will have brought him Eliogabalo’s good graces and that he intends to ask the Emperor’s permission to be joined in marriage. Eritea goes to see Eliogabalo and requests the marriage that, alone, can restore her honour. Under the despairing gaze of Giuliano who is smitten with Eritea, the Emperor gives his promise. However, when left alone with Lenia and Zotico, he admits that he has been disappointed with his amorous adventures with Eritea and dispatches Lenia to find him new sources of pleasure. Alessandro asks the Emperor for his permission to marry Gemmira. Hearing that Gemmira is the most beautiful woman in Rome, Eliogabalo gives his blessing… but secretly plans to seduce her. He instructs Lenia and Zotico to organise a senate of women to win her over. The young Atilia declares her love for Alessandro, but he spurns her. Their encounter is interrupted by Gemmira who doubts her lover’s fidelity. Refusing to be escorted into the Senate by Atilia, Gemmira relies on the assistance of Lenia, whom she believes to be more trustworthy. In the Senate, Eliogabalo receives the Roman women and organises an erotic version of blind man’s bluff to decide who will be able to legislate. With their eyes blindfolded, the female senators will have to guess who is kissing them… As Eliogabalo manages to embrace Gemmira, Eritea bursts in and reproaches him. Her ill‑timed tantrum ruins the Emperor’s carefully crafted plan.

Act II

Atilia once again declares her love to Alessandro. Giuliano and Eritea bemoan their absurd situation: she must shun the love of the man she loves to win the hand of a man she abhors and whom she knows to be unfaithful. Eliogabalo concocts another scheme to gain Gemmira’s favours. He orders a banquet during which he will slip a sleeping draught into Gemmira’s drink and poison Alessandro, who has become too popular with the army for Eliogabalo’s liking. When Alessandro encounters Gemmira at the palace, he expresses his astonishment at her attentions for the Emperor and reproaches her for what he perceives as her inconstancy. Eritea and Giuliano are caught in an embrace by the Emperor. The latter proposes a deal to Giuliano: if Giuliano gives him his sister Gemmira, he will let Giuliano have Eritea. Giuliano decides he would sooner die than have to choose between losing his sister or his lover. The preparations for the banquet are underway. Zotico has pre‑ pared wine mixed with poison for Alessandro whilst Lenia keeps the sleeping draught that will leave Gemmira helpless. However, the banquet is interrupted by the flight of a bird of ill omen. Once again, Eliogabalo is forced to put off his plans.

Act III

Gemmira and Eritea curse Eliogabalo and unmask Lenia. They exhort Giuliano to commit regicide. At first hesitant, he allows himself to be persuaded. He then asks his sister to pretend to accept to marry the Emperor the following day. As Lenia tells Eliogabalo that she no longer trusts Gemmira, the guards enter and demand the death of the Emperor. Zotico advises Eliogabalo to shower the guards with gold: the handout calms the revolt. Eliogabalo blames the insurrection on Alessandro. Zotico suggests organising a gladiatorial combat during which Alessandro can be killed. Lenia advises Eliogabalo to profit from the compulsory presence of Giuliano and Alessandro at the games to seduce Gemmira. Giuliano finds his courage but Alessandro dampens his fervour. Eliogabalo commands them to attend the gladiatorial combat. Alessandro pretends to leave but then hides. The Emperor is eager to know if Giuliano has come to a decision: Giuliano informs Eliogabalo that he will have his sister the next day. Gemmira arrives and confirms to Eliogabalo that she will be his. However, noticing Alessandro hiding in the room, she cannot bring herself to kiss Eliogabalo. Furious, he vows retribution. Alessandro despairs at female fickleness. Atilia enters and conti‑ nues to beg for his love. Alessandro promises her that if he cannot marry Gemmira, he will marry her instead. Just then, Gemmira’s sudden arrival sparks a new quarrel between the two lovers. Giuliano reconciles them by explaining his intentions to Alessandro. The three young people debate whether to murder the Emperor and, under the influence of Alessandro, reject the idea. At the Coliseum, Giuliano opens the games and notices that the Emperor is absent. The star gladiator pounces on Alessandro but he is stopped before he can injure him. Tipherne admits that he has acted on the orders of Zotico. Gemmira arrives and tells how Eliogabalo tried to ravish her and how she was saved by a patrol which killed her attacker. Atilia announces that Zotico and Lenia have been lynched by a mob. The Praetorian Guard declares Alessandro emperor and the four lovers are united by two marriages.