At the home of the richest man in Vienna, the Major-domo is overseeing a grand evening of music, food and fireworks. A Music Master, on behalf of the Composer, is complaining that their opera, Ariadne auf Naxos, is to be followed by a vulgar comedy.
The directors and performers of the opera and the comedy mingle uneasily, and then the Major-domo announces that, due to time constraints, their works must be performed simultaneously, requiring cuts to the opera. The horrified Composer, who at first announces that he would rather burn the score, accedes, and work begins. His lead singers, the Tenor and the Prima Donna, each suggest that cuts take place in the other’s role.
The zesty and charming Zerbinetta, star of the comedy troupe, attempts to bring the Composer down to earth, suggesting that his heroine, Ariadne, is unrealistic. Suddenly encouraged, the Composer changes his attitude, as the performance is to begin. But as the comedy troupe prepares to go onstage, he is newly outraged, regretting his willingness to alter his opera.
Ariadne, abandoned by Theseus, lies motionless, attended by the nymphs Naiad, Echo and Dryad. She awakes, but expresses inconsolable sorrow at her romantic heartbreak. Meanwhile, Zerbinetta and Harlequin comment from the side, and Harlequin even tries, to no avail, to enliven Ariadne with a song. The comedians begin another effort to lift Ariadne’s spirits.
Zerbinetta sends her troupe away, and faces Ariadne directly, sharing a feminine solidarity with her, and imploring Ariadne to find an inner strength despite the offenses of men. Shortly after, as if to prove her point, Harlequin tries to seduce Zerbinetta, but is rebuffed. The rest of the troupe tries to convince Zerbinetta that she should give up trying to console Ariadne.
The nymphs reappear, highly excited by the arrival of a ship, with the handsome young god Bacchus at the helm. Ariadne is coaxed from her cave to meet him, but resists him, fearing that he is actually the embodiment of death. They resolve their mutual misunderstandings and sing a sumptuous love duet. Zerbinetta briefly appears from the wings, acknowledging her willing surrender whenever a new love comes along.