In 1556, Emperor Charles V abdicated, celebrated his own funeral and retired to the monastery of San Jeronimo at Yuste. His son Philip II is now on the throne of Spain. To seal the peace between France and Spain after a long war, Philip marries Elisabeth of Valois, the daughter of Henry II, the French King, who has long been betrothed to his son Don Carlo.
The cloister of the Yuste monastery
A Monk prays before the gates of the tomb of Charles V. Carlo starts at the sound of the voice — is this his grandfather, the Emperor?
Carlo’s friend Rodrigo, the Marquis of Posa, joins him and advises him to conquer his sorrow caused by losing his bride by a noble enterprise — that of freeing Flanders. The two vow to live and die together.
Outside the Yuste monastery gates
Outside the monastery, which no woman but the Queen may enter, her ladies while away the time with the song Princess Eboli sings.
The Queen enters, followed by Posa, who brings Elisabeth a letter from her mother and, under cover of the letter, a note from Carlo. While Eboli and Posa chat about the latest Paris fashions, Elisabeth reads the note, which tells her to trust Posa. In two broad strophes, Posa urges Elisabeth grant, Carlo, an interview, while Eboli (in asides) reveals her love for Carlo and her hope that he loves her. Dismissing her ladies, Elisabeth consents to Posa’s request. Carlo, at first controlled, asks Elisabeth to obtain the King’s permission that he should leave for Flanders, but then his emotions overcome him and he falls to the ground in a swoon. On recovering, he clasps Elisabeth in his arms, defying the world. But she exclaims, “Then smite your father. Come stained with his murder, to lead your mother to the altar.” Carlo runs off in despair.
Philip enters, angry to find the Queen unattended. Coldly he orders the lady-in-waiting who should have been with her to return to France. Elisabeth consoles her. The company leaves, but Philip orders Posa to remain: has he no favour to ask for? “Nothing for me,” replies the Marquis, “but for others”; and, invited to speak freely, he describes the terror and destruction being wrought in Flanders. “At this bloody price,” says Philip, “I have paid for the peace of the world.” “The peace of a graveyard,” Posa replies: one word from Philip could change the world and set people free. The King, struck by Posa’s fearless honesty, confides to him his suspicions about his wife and his son, and appoints him his personal counselor, but bids him beware the Grand Inquisitor.
The Queen’s gardens
Carlo enters, reading a note of midnight assignation which he believes has come from Elisabeth. When Eboli (who wrote the note) enters, masked, Carlo mistakes her for Elisabeth and pours out his love. Too late, the mistake is revealed, and Eboli guesses his secret. Posa enters and tries to silence her, but in a tense trio, she bids them beware the fury of a woman scorned. Posa asks Carlo to entrust to him any incriminating papers he may be carrying, and after a moment’s hesitation — can he trust the King’s new favourite? — Carlo does so.
A large square before the Basilica of Nuestra Señora de Atocha
The people gather to acclaim their King. Monks escort some Inquisition victims across the square; a splendid auto da fe, or public burning of heretics, is among the attractions of the day. Philip appears from the church and swears solemnly to serve God with fire and the sword. Suddenly a group of men cast themselves at his feet, and Carlo, who has led them there, announces that they are deputies from Flanders. The Flemings break into an eloquent plea for their country. Philip orders them to be taken away. All — except the monks — urge him to show mercy. At the close of the huge ensemble, Carlo asks his father to send him to Flanders as regent, and when Philip refuses, he draws his sword on the King. No one dares to disarm him until Posa steps forward. The King rewards Posa by making him a Duke, and the festive chorus is resumed.
The King’s study
Philip is alone in his study and reflects gloomily on his loveless, careworn life. The Grand Inquisitor is announced. Philip doubts whether he will be forgiven if he condemns his son to death; the Inquisitor demands that Posa should be handed over to the Inquisition. Philip refuses. The Inquisitor declares that Philip himself is in danger of being summoned before the Inquisition and leaves.
Elisabeth rushes in, distressed that her jewel casket has been stolen. Philip, who has it, opens it and draws out a portrait of Carlo. Elisabeth reminds him that she was once betrothed to the Prince, but he calls her an adulterous wife. She swoons. Eboli and Posa enter, and in a quartet, Philip curses his unworthy suspicions, Eboli expresses her regret (for it was she who stole the casket), Posa decides that the time has come for him to take action, and Elisabeth, reviving, laments her unhappy life in this friendless country.
The two women are left alone. Eboli confesses that drive by jealousy, she denounced Elisabeth to the King. At Eboli’s further confession, that she has been Philip’s mistress, Elisabeth tells her to choose, the following day, between exile and the veil, and leaves. Eboli curses the gift of fatal beauty that has caused her ruin. Her thoughts turn to Carlo, and she resolves to save him during the one day this is left to her.
Don Carlo’s prison
Posa comes to bid Carlo farewell; he is marked for death since Carlo’s incriminating papers have been found on him — but Carlo can go free, to save Flanders. A shot is fired, and Posa falls. Quickly he explains that Elisabeth awaits Carlo at the Yuste cloister; he dies content since by his death he secures the happy future of Spain. Philip enters, to return to Carlo his sword. A warning bell rings out; a crowd storms the prison, demanding the Prince. The tumult is quelled by the Grand Inquisitor, who orders the sacrilegious mob to fall on its knees before the King.
The Cloister at Yuste
Elisabeth invokes the spirit of Emperor Charles: may he carry her prayers to the Eternal Throne. Carlo enters and declares that he is done with dreaming; now he will save Flanders. The two take a solemn farewell, hoping to meet in a better world: “And forever! Farewell!” Philip and the Inquisitor have overheard them; the King delivers his son to the Inquisition. The gates of the Emperor’s tomb open and the Monk steps forth. He enfolds Carlo in his mantle and leads him into the cloister, recognized as Charles V by everyone present on stage.