Dario is announced. However, Megabise (also in love with Semira) has Arbace led into the chamber in chains, announcing that the bloody sword used to kill Serse had been found in his possession. Arbace is now condemned to death. However, Artaserse, who had long been a friend of Arbace, doubts his guilt. He releases Arbace from prison and allows him to escape through a secret passage. Megabise, encouraged by Artabano, then goes off to lead a rebellion against Artaserse. In the Temple of the Sun Artaserse, surrounded by his nobles, swears to maintain the rights, laws, and customs of his subjects and is about to pledge this by drinking from a sacred cup, unaware that Artabano has poisoned the drink. Before Artaserse can drink from the cup, news arrives that Megabise and his men are at the palace gates. The danger is averted when Arbace kills the traitor, confirming to Artaserse that his friend is innocent. Artaserse then offers the sacred cup to Arbace instead so that he may pledge his innocence. Artabano is now faced with seeing his son die or confessing the truth. He confesses to all that he has poisoned the cup, intending to kill Artaserse and that he had also assassinated Serse. Artabano is led off in chains. Artaserse, out of his love for Semira and his gratitude to Arbace, condemns their father to eternal exile rather than death. The opera ends with the two pairs of lovers reunited and the jubilation of all. Vocal set pieces Act I, scene 1 - Aria of Mandane, "Conservati fedele" Act I, scene 2 - Aria of Arbace, "Fra cento affanni" Act I, scene 3 - Aria of Artabano, "Su le sponde del torbido Lete" Act I, scene 5 - Aria of Artaserse, "Non mi dir ch'io sono ingrato" Act I, scene 6 - Aria of Semira, "Bramar di perdere" Act I, scene 10 - Quartet of Mandane, Arbace, Artaserse, and Artabano, "Deh, respirar lasciatemi" Act II, scene 1 - Aria of Artaserse, "Rendimi il caro amico" Act II, scene 4 - Aria of Megabise, "Non temer ch'io mai ti dica" Act II, scene 5 - Aria of Mandane, "Pace e calma in questo sedno" [a non-Metastasian text] Act II, scene 6 - Aria of Semira, "Se del fiume altera l'onda" Act II, scene 9 - Accompanied recitative for Artabano, Mandane, and Arbace, "Io gelo" Act II, scene 9