Walter is betrothed to Anna of Rehberg, niece of the Margrave of Biberich. One May evening while wandering on the banks of the Rhine, Walter encounters the beautiful orphan Loreley and seduces her. He summons his friend Hermann and tells him that he is torn between "lawful and unlawful love". Although Hermann is himself in love with Anna, he counsels Walter to be true to his fiancée. When Walter next encounters Loreley, he tells her that although he loves her, he will marry Anna. He leaves Loreley who has fallen to the ground in a faint. Herman, lamenting that he has yielded his beloved Anna to such a man, appeals to the God of the Rhine and dedicates himself to avenging the wrong done to Anna.