Cloister in the monastery of Yuste.
A friar is praying at the tomb of Charles V. Don Carlos, Infante of Spain, recalls his first meeting with his beloved Elizabeth de Valois to whom he was betrothed. But she is now the wife of his own father Philip II and Queen of Spain (Aria: “Io la vidi e il suo sorriso”).
Rodrigo, Marquis of Posa, enters, having returned from the Netherlands.When he announces the rebellion of that region cruelly oppressed by the Spanish crown, Carlos starts with joy. He can confide his love of Elizabeth to his friend, who is anxious to help him. Rodrigo urges him to forget his troubles and go to the Netherlands to help put an end to the religious persecutions there. After their conversation, Carlos and Rodrigo swear mutual friendship, while the King and Queen cross the cloister to enter the monastery (Duet: “Dio, che nell’alma infondere”).
A charming spot outside the cloister of Yuste.
The ladies of the court await the Queen, while Princess Eboli sings a song accompanied by the page Tebaldo (Aria: “Nel giardin del bello”). When Elizabeth arrives, she encounters the Marquis of Posa, who hands her a letter from her mother, together with a concealed note from Carlos begging her to trust Rodrigo. The Marquis in fact invites her to meet Philip’s son and to plead his cause with the King (Aria: “Carlo, ch’è sol”). Meanwhile Princess Eboli interprets the agitated state of mind of Carlos, whith whom she is secretly in love, as proof that he loves her too. Now in the Queen’s presence, Carlos asks her to intercede with the King to let him leave for the Netherlands. But their dialogue quickly turns into a declaration of love, interrupted by Elizabeth who reminds her stepson of the impossibility of realizing their union (Duet: “Perduto ben, mio sol tesor”). He goes out in despair, leaving the Queen by herself to implore divine help.When the King enters and finds his wife without her royal retinue, he banishes the Countess of Aremberg for having left Elizabeth unattended. The lady’s departure is accompanied by the soft words of Elizabeth (Aria: “Non pianger, mia compagna”).
Philip enjoins the Marquis of Posa to stay with him, and Rodrigo tells him of the cruelties inflicted upon the Netherlands, begging him to grant them autonomy. The King rejects the request. But, after reminding him of the Grand Inquisitor’s awesome power, he reveals to the Marquis the troubles that are on his mind. He is aware of the feelings that unite Carlos and Elizabeth, and appoints Rodrigo to keep watch on the couple. The Marquis happily welcomes the proposal and takes his leave after the King has again put him on his guard against the Grand Inquisitor (Duet: “O signor, di Fiandra arrivo”).
The Queen’s gardens in Madrid.
At the Queen’s ball, the tired Elizabeth asks Princess Eboli to substitute her. Eboli puts on the Queen’s cloak, jewels and mask, and thus disguised hands the page a love letter to be delivered to Don Carlos.
Carlos has been deceived by a note inviting him to a nocturnal tryst with Elizabeth. But Princess Eboli turns up instead, wearing a veil, and Carlos declares his love (Duet: “Sei tu, bella adorata”). When Carlos realizes he has been tricked, he fails to hide his amazement.
The Princess then understands the secret relationship between Carlos and the Queen. Distraught with jealousy, she swears to get her revenge. Rodrigo vainly tries to justify his friend and threatens to impose silence on Eboli by death (Trio: “Al mio furor sfuggite invano”). The Marquis of Posa asks Carlos to give him the documents from the Netherlands that are in his keeping.
A large square in front of Our Lady ofAtocha.
The people rejoice as the friars conduct to the stake the prisoners condemned by the Holy Office (Chorus: “Spuntato ecco il dì d’esultanza”). After the court has entered, a group of Flemings, led by Carlos, throw themselves at the King’s feet, imploring justice for their country.
Philip refuses to hear them and gives orders for the rebels to be taken away (Concertato: “Sire, no, l’ora estrema”). Carlos, having in vain requested permission from his father to go to the Netherlands, draws his sword and sides with the Flemings. The King replies to this affront by ordering his guards to disarm his son, but no one dares approach him. Only Rodrigo’s intervention avoids a direct clash. Removing the Infante’s sword, the Marquis hands it to the King.The procession continues on its way to attend the burning of the heretics, while a voice from heaven invokes eternal peace.
The King’s private rooms in Madrid.
Philip meditates on the difficulties of life as a sovereign (Aria: “Dormirò sol nel manto mio regal”). He furthermore requests punishment of his son by the Grand Inquisitor, who in his turn proposes that Rodrigo also be condemned as guilty of Carlo’s rebellion. But the King opposes this injunction and, after a heated argument, finds himself again alone. Elizabeth enters, reporting the disappearance of a casket.Without her knowledge, the casket, in which was hidden a portrait of Carlos, has been delivered by Princess Eboli to the King.
In vain the Queen proclaims her honesty while her husband accuses her of adultery.
Princess Eboli now enters, overcome with remorse, with Rodrigo, who realizes that he can save Carlos only by sacrificing his own life (Quartet: “Ah! sii maledetto, sospetto fatale”).
The Princess confesses her guilt to the Queen, who orders her to leave the court. Eboli deplores the effects of her beauty and vows to herself that she will save Carlos from his impending danger (Aria: “O don fatale, o don crudel”).
Don Carlo’s prison.
Rodrigo announces to Carlos, who has been thrown into prison by his father, that he is soon to be released. To relieve him of all blame, Rodrigo has admitted to being in possession of the documents which the Infante had entrusted to him (Aria: “Per me giunto è il dì supremo”). Rodrigo is shot in the back.
As he dies, he tells Carlos of a rendezvous that has been fixed with Elizabeth in the monastery of St. Yuste, and reminds him of the Flemish cause. Philip has come to the prison to free his son, who accuses him of having killed Rodrigo. Don Carlos also claims that Rodrigo sacrificed his life for him. But Philip, too, mourns the death of his friend Rodrigo and the proud nobility of his spirit. Meanwhile the bystanders are indignant at the horrors of the kingdom of Spain.
Praising the Infante, the people burst into the prison. Only the sudden appearance of the Grand Inquisitor calms the anger of the people, who kneel before their sovereign.
Cloister of the monastery of Yuste.
Elizabeth recalls the joys of childhood and her love of Carlos (Aria: “Tu che le vanità conoscesti del mondo”). Once again together, the lovers exchange a last farewell. The Infante is leaving Spain for the Netherlands to fight for the freedom of the Flemings (Duet: “Ma lassù ci vedremo”). But their leave-taking is interrupted by the sudden entry of Philip, the Grand Inquisitor, and the guards of the Holy Office.As Carlos is about to be arrested, Charles V appears and, to the terror of all present, seizes his grandson and drags him off.