Moonbeam is a profane oratorio based on Gustavo Adolfo Bécquer’s homonymous legend. It takes place in the town of Soria and possibly around San Juan Monastery or San Polo Monastery.

It tells the story of a young idealist nobleman named Manrique, who is able to discern the outline of a beautiful young woman while strolling around the monastery ruins. He convinces himself she is the woman of his dreams, and so, he starts following her unreal trail. But, after a few days desperately searching for her, he realises he was not following a beautiful blue-eyed and dark-haired foreign woman, but a ray of moonlight passing through branches and leaves.