Opera in three acts by Johann Adolf Hasse. Performed in Italian with German surtitles.
The Indian king Poro and his army have been defeated by Alessandro. Poro is greatly distressed and is tormenting his lover Cleofide, the queen of a neighbouring Indian state, by insinuating that she is ready to fall into Alessandro's arms. Gandarte, Poro's general, urges him to flee and offers to exchange clothes with Poro by way of disguise. Poro meets Alessandro and his general Timagene. He passes himself off as one of Poro's soldiers by the name of Hasbytes. His fearlessness impresses Alessandro. He gives him a precious sword and sends him on an official mission to Poro. But Hasbytes/Poro can only think of revenge. Alessandro frees Erissena, Poro's sister, from Indian opportunists. Timagene falls in love with Erissena but she only has eyes for Alessandro. This stirs up Timagenes' hate for Alessandro who had killed his father. He decides to ally himself with Poro. Poro's jealousy flares up again. When Cleofide points out how much his jealousy has already destroyed, Poro promises to mend his ways. Cleofide is preparing for her last diplomatic negotiations with Alessandro, and this sparks off Poro's jealousy once more. When he bursts into the meeting between Cleofide and Alessandro, Cleofide turns to Alessandro and ostentatiously pretends to declare her love for him. Alessandro withdraws by breaking off the negotiations. Cleofide and Poro are left to argue. Poro attacks Alessandro again. Cleofide is suspected of having deceived Alessandro. Poro torments her with his jealousy again, and she threatens to kill herself. This brings Cleofide and Poro closer. When they are surprised by Alessandro, Poro/Hasbytes protects Cleofide by taking all the blame upon himself. Alessandro releases Cleofide but not without taking her to task about associating with traitors. Poro/Hasbytes is left behind as a prisoner with Timagene who is conspiring with him against Alessandro, and releases him.
Alessandro's soldiers are demanding Cleofide's head. Alessandro can only protect her by marrying her. He asks Cleofide for her hand in marriage. Gandarte appears as the supposed Poro and is ready to sacrifice himself for Cleofide. Pleased by this turn of affairs, Alessandro rewards Poro/Gandartes for his readiness to make such a sacrifice by setting them all free.
Gandarte wishes to return Cleofide to Poro. He hopes to win Erissena in return. But she brings news that Poro has killed himself. Cleofide collapses with despair. All she wants to do is die. Meanwhile Gandarte learns that the news of Poro's death is just a rumour spread by Timagene to ensure that he does not fall out of favour with Alessandro. He asks Erissena not to tell Cleofide for the moment but instead to remind Timagene of his letter in which he promised to trap Alessandro in an ambush.
A misunderstanding causes this letter to reach Alessandro. But instead of punishing Timagene, he leaves him to search his own conscience. Timagene abandons his plans for revenge. In vain Poro/Hasbytes tries to tempt him with the prospect of wealth and Erissena's hand in marriage. Erissena talks about the wedding preparations. Poro almost goes mad with jealousy, and Gandarte considers it his duty to kill Alessandro. Cleofide has resolved to sacrifice herself for her country by pretending to go through the process of marrying Alessandro, and then killing herself during the wedding ceremony. When Poro learns of this, he discloses his identity and wishes to die with his lover. At the last moment, Alessandro is able to prevent this catastrophe.