At Covent Garden, the performance of Gluck’s masterpiece Orpheus is jammed. Everyone, from Prime Minister Pitt and other prominent dignitaries seated in forward boxes to commoners in the rear, enjoys the performance. A scattering of aristocratic French refugees attends, including the Comtesse de Tournay. Chauvelin also is in the audience.

During an intermission, Lord Grenville, head of the foreign office, visits the box where the comtesse and her children sit, guests of the coarse-but-kindly Lady Portales. Grenville reports that the French carnage continues apace; the comtesse, thinking of her endangered husband, feels anguish.

Sir Percy and Lady Blakeney arrive late to their box; Marguerite, wearing a new outfit that will shortly become the rage, waves to members of the audience, who salute her, as do those in the royal box. Visitors throng around her, and Sir Percy discreetly departs to make way for them. Marguerite finally dismisses them to focus on the music. The third act commences, and Marguerite, who loves music, is enthralled. For a moment, sitting by herself, her troubles disappear.

Chauvelin steps into the box, sits behind her, and whispers that her brother is a traitor—he’ll be executed unless she helps him find the identity of the Scarlet Pimpernel.