Original version in Italian

Place: Classical Pherae, Thessaly
Act 1
A herald announces to the people of Thessaly that King Admeto is gravely ill and that there is little hope. Evandro calls upon all to pray to the oracle at the temple of Apollo. Alceste joins them and asks Apollo for pity. The oracle says Admeto can be rescued if another voluntarily sacrifices his life. This causes great consternation. Alone, Alceste agonizes whether to give her life for that of her husband.

Act 2
In a dense forest dedicated to the gods of the underworld, Ismene asks Alceste why she is leaving her husband and children. Alceste tells Ismene of her intentions. Meanwhile, Admeto has a miraculous recovery to the joy of all Thessaly. Evandro tells him that someone has apparently sacrificed himself for the king. When Alceste appears, he questions her until she confesses. The desperate king hurries into the temple to plead with the gods. However, Alceste says good-bye to the children.

Act 3
The decision of the gods is not revoked. The people lament the approaching death of Alceste. Having said good-bye to Alceste, Admeto decides to follow her into death. Then the heavens open, Apollo descends and proclaims that the gods have given them their lives as a reward for their steadfast love.

Paris version

The overture is stately, noble, and tragic, looking ahead to some of Mozart's minor-key works. The choir propels much of the action in the first two acts, and Gluck's vocal settings are particularly elegant, taking advantage of the French language's smooth rhythms, although the writing is rather static in its sad dignity.

Act 1
King Admetus is dying, and his people are in despair. The god Apollo refuses their animal sacrifice, proclaiming that Admetus will live only if another person is sacrificed in his place. Queen Alceste believes she is the victim Apollo has in mind, but declares she will surrender her life only for love. (Aria: "Divinites du Styx")

Act 2
The people celebrate the king's recovery. Admetus does not realize that Alceste has volunteered to die in his place, and his wife won't give herself up until the record is set straight. When he learns the truth, Admetus believes that Alceste is in effect abandoning him, and would prefer to die himself.

Act 3
The people, sorrowing again, prepare the royal couple's children for sacrifice in their place. Admetus' friend Hercules arrives and promises to conquer death on his behalf, and travels to Hades. Meanwhile, Alceste has already arrived at the gates of hell; Admetus tries to dissuade her, but she is sacrificing herself for love, rather than as some heroic act. She dies, but Hercules rescues her—except that now Alceste seems nearly insane. Apollo arrives, promises Hercules immortality, and leaves Admetus and Alceste in a world that seems devoid of death. The work ends with a joyful chorus.