In the Woodstock Castle park, the country-folk acclaim Enrico (King Henry II) upon his return from his wars in Ireland. As they greet him, Leonora (Queen Eleanor) appears, followed by the King’s page, Arturo. It is revealed that Arturo was once taken under Leonora’s protection as a young orphan, and consequently feels deeply indebted to her. As a result of these feelings, he has told her a powerful secret: that Enrico has a mistress, and that upon his departure for Ireland he lodged her in a tower at Woodstock and left Arturo to watch over her. Her identity is so secretive that even Arturo does not know her name. Leonora realizes that the page has fallen in love with this mysterious woman. Leonora encourages him by suggesting that she will help him win her for himself, but at the same time she clearly seeks revenge upon her rival.