Act I
In the main square in the city of Pherae in Thessaly, the town crier is announcing King Admetus’ imminent death to his sorrowful people. The King’s confidant, Evander, is asking the people to offer sacrifices to the gods and consult an oracle, asking for advice. Admetus’ wife, Alcestis comes out of the palace with her children Eumelus and Aspasia. The Queen also wants to join the people in the sacrifice and consult the oracle.
In Apollo’s temple, the high priest and his ministers are invoking god and offering sacrifices. Alcestis arrives with her retinue and makes a sacrifice to god. Her sacrifice is accepted; the temple is illuminated, perfumed and begins shaking. Apollo’s oracle pronounces his verdict: Admetus will die unless someone else is sacrificed in his place. Initially aghast and confused, Alcestis wonders who might love Admetus so much that they would sacrifice their own life. She decides to offer her own life in exchange for her husband’s. Evander and the confidant Ismene rush to tell her that Admetus, on his death bed, is asking to see his wife one last time. Once Alcestis has left, the priests and people join Evander and Ismene to discuss the latest turn of events – all unaware of the Queen’s vow. Nobody has the courage to offer their own life to save the King.
Act II
At night, Ismene tries to stop Alcestis in vain going into the sacred woods dedicated to the gods of the underworld. When she hears an unknown voice in the woods, Alcestis is terrified. Her courage gradually returns and, despite the warnings from the infernal gods, she takes the oath that condemns her to death in Admetus’ place. Alcestis asks the gods to be allowed to embrace her husband and children one last time before descending into Hades, and they consent.
In the palace, the courtiers are celebrating the King’s unexpected recovery. Evander also joins in the rejoicing and tells the King about Apollo’s oracle, certain that someone has sacrificed their own life for his good health. While the King is praising the generosity of this anonymous hero, Alcestis arrives with her retinue. Admetus runs to embrace his wife and does not understand why she is visibly upset and refuses to answer his questions. The Queen gradually gives in: she reminds Admetus about Apollo’s oracle and reveals she has promised herself to the gods in exchange for the King’s recovery. Admetus is furious. He refuses Alcestis’ sacrifice, putting her love before her duties as a wife and mother. He leaves with Evander to return to the oracle, convinced this response was wrong or misconstrued. Once she is left alone with Ismene and her ladies-in-waiting, Alcestis feels her strength fading and prepares herself for death, much to the sorrow of her confidant and retinue. She then gets up to take her children to Admetus so he can look after them.
Act III
Admetus is telling Evander that Apollo’s oracle remained silent. Admetus cannot die for his wife, so he must resign himself to her death. While the King is lamenting his fate, Alcestis arrives with the children, Ismene and her retinue. In exchange for her sacrifice, the Queen asks Admetus never to marry again. She then entrusts the two young children to the King and says farewell. Alcestis asks her children to look after her tomb. While everyone is lamenting the Queen’s fate, a group of infernal gods burst into the room: her time is up, Alcestis has to go to the underworld. Admetus offers himself one last time instead of his wife, drawing his sword to defend her but it is all to no avail. Alcestis is led away by the gods of Hades. Distraught, Admetus wants to take his own life so he can join his wife straightaway. However, Evander and Ismene stop him, pointing at a bright flash up in the clouds. Apollo himself comes down from the skies and turns to the King. The gods took pity on the couple and are returning Alcestis, who embraces her husband and children. The King orders another sacrifice straightaway to thank Apollo.