Act II. _Filina's_ boudoir at the castle. The actress sings of her
pleasure in these elegant surroundings and of _Wilhelm_. _Laertes_ is heard without, singing a madrigal to _Filina_, "Belle, ayez pitié de nous" (Fair one, pity take on us).
He ushers in _Wilhelm_ and _Mignon_, then withdraws. _Mignon_, pretending to fall asleep, watches _Wilhelm_ and _Filina_. While _Wilhelm_ hands to the actress various toilet accessories, they sing a graceful duet, "Je crois entendre les doux compliments" (Pray, let me hear now the sweetest of phrases). Meanwhile _Mignon's_ heart is tormented with jealousy. When _Wilhelm_ and _Filina_ leave the boudoir the girl dons one of _Filina's_ costumes, seats herself at the mirror and puts on rouge and other cosmetics, as she has seen _Filina_ do. In a spirit of abandon she sings a "Styrienne," "Je connais un pauvre enfant" (A gypsy lad I well do know). She then withdraws into an adjoining room. _Frédéric_ enters the boudoir in search of _Filina_. He sings the gavotte, "Me voici dans son boudoir" (Here am I in her boudoir). _Wilhelm_ comes in, in search of _Mignon_. The men meet. There is an exchange of jealous accusations. They are about to fight, when _Mignon_ rushes between them. _Frédéric_ recognizes _Filina's_ costume on her, and goes off laughing. _Wilhelm_, realizing the awkward situation that may arise from the girl's following him about, tells her they must part. "Adieu, Mignon, courage" (Farewell, Mignon, have courage). She bids him a sad farewell. _Filina_ re-enters. Her sarcastic references to _Mignon's_ attire wound the girl to the quick. When _Wilhelm_ leads out the actress on his arm, _Mignon_ exclaims: "That woman! I loathe her!"
The second scene of this act is laid in the castle park. _Mignon_, driven to distraction, is about to throw herself into the lake, when she hears the strains of a harp. _Lothario_, who has wandered into the park, is playing. There is an exchange of affection, almost paternal on his part, almost filial on hers, in their duet, "As-tu souffert? As-tu pleureé?" (Hast thou known sorrow? Hast thou wept?). _Mignon_ hears applause and acclaim from the conservatory for _Filina's_ acting. In jealous rage she cries out that she wishes the building might be struck by lightning and destroyed by fire; then runs off and disappears among the trees. _Lothario_ vaguely repeats her words. "'Fire,' she said! Ah, 'fire! fire!'" Through the trees he wanders off in the direction of the conservatory, just as its doors are thrown open and the guests and actors issue forth.
They have been playing "A Midsummer Night's Dream," and _Filina_, flushed with success, sings the brilliant "Polonaise," "Je suis Titania" (Behold Titania, fair and gay). _Mignon_ appears. _Wilhelm_, who has sadly missed her, greets her with so much joy that _Filina_ sends her into the conservatory in search of the wild flowers given to _Wilhelm_ the day before. Soon after _Mignon_ has entered the conservatory it is seen to be in flames. _Lothario_, obedient to her jealous wish, has set it on fire. At the risk of his life _Wilhelm_ rushes into the burning building and reappears with _Mignon's_ fainting form in his arms. He places her on a grassy bank. Her hand still holds a bunch of withered flowers.