The Queen rushes in and asks the King to help her look for a casket of jewels which have disappeared from her room. The King shows her that it is on the table. He tells her she must open it. She does so. At the top is a portrait of Carlos. The King is very angry and accuses her of adultery. She faints. The King calles Eboli and Rodrigue for help. The King feels sorry for his suspicion, but Eboli feels even more sorry because it was she who had taken the casket because she was jealous of Carlos and Elisabeth. It was she who had suggested the King should look in the jewel case. Rodrigue feels he can only save his friend by offering himself to be killed instead of Carlos. The King and Rodrigue leave. Eboli throws herself at the feet of the Queen, who has now revived, and confesses that she herself is guilty of adultery because she had slept with the king. Elisabeth remains calm, but tells Eboli to go away from her for ever and to live in a nunnery. When Eboli is left alone she expresses her feelings of terribly misery. Before she goes to the nunnery she has one more thing to do: to try to save Carlos from being put to death.