ACT I
Admeto is dying. His wife Alceste prays to Apollo, and a voice from the god's statue says that Admeto must die unless someone else sacrifices their life in his pace.
Antigona, a Trojan princess, her companion Meraspe arrive disguised as sheperdesses. Antigone, who had been betrothed to Admeto, accuses him of unfaithfulness. Alceste kills herself to save her husband; Trasimede, Admeto's brother, identifies Antigona from a portrait.
ACT II
Ercole rescues Alceste from hell. Antigona's portrait is brought to Admeto, who is attracted to her but remembers his lost Alceste: he notes the portrait's resemblance to the "shepherdess", but is told that Antigona died at Troy.
Alceste returns disguised as a soldier and finds Antigona admiring Admeto's portrait.
ACT III
Antigona's identity is revealed to Admeto and when Ercole tests him by saying that he had failded to rescue Alceste, Admeto appears unmoved. The betrothal of Admeto and Antigona is arranged, but Trasimede wants Antigona for himself and plans to kill his brother. As Admeto and Antigona enter, he hides, unaware that Alceste also has concealed herself in the room: he steps forward to stab Admeto, but is intercepted by Alceste. She reveals her identity and is reunited with her husband, yielded al last by Antigona.