The three friends meet up at the dingy theatre, where they're met by the manager. Dorian hates the guy more than ever, but Lord Henry claims to like him – then again, we're never sure how serious he is.
The theatre sounds hellish – it's hot, noisy, and grotesque. Dorian promises that Sibyl will make this outing worth it, and Basil believes him.
Finally, Sibyl comes on stage as Juliet, and Henry and Basil are both enraptured by her; Basil even jumps up and applauds. Her beauty is more remarkable than ever.
Sibyl's acting, however, is worse than ever before. Every spark of her amazing talent is gone, and she's absolutely terrible.
Dorian feels betrayed, and his friends are terribly disappointed. They wait for the famous balcony scene to pass judgment – and she fails miserably. Everyone in the theatre is bored and disappointed.
Henry and Basil leave the theatre at intermission; Basil is willing to seek an explanation, saying that Sibyl must be ill. Dorian, however, can't believe it – he doesn't know what happened to the Sibyl he loves.
Dorian, weeping, tells Henry and Basil to leave him alone with his heartbreak.
The rest of the play is a disaster. Dorian sits through it, miserable, then rushes backstage to confront Sibyl.
The girl is overjoyed to see her fiancé. She happily tells him that she will never act well again – and, to make matters worse, it's Dorian's fault. Before she met Dorian, acting was the only real world to her, but now that she's in love with him, he's everything to her. She says that it would be profane for her to act at being in love on stage, since she's found real love with Dorian.
This explanation isn't enough for Dorian, and he tells Sibyl that he doesn't love her anymore. He goes on in a fit of passion to tell her that she's basically worthless – he can't believe he ever loved her, and he wishes he hadn't. To add insult to injury, he calls her a "third-rate" actress.
Sibyl is stunned and horrified – she can't believe Dorian's saying this (neither can we!). She begs him to reconsider, but, instead, he coldly leaves her in tears.
Dorian flees the theatre, not paying attention to where he's going. He ends up in the flower market in Covent Garden, and eventually makes his way home in a cab around dawn.
When he gets back to his opulently decorated house, Basil's portrait catches his eye. For some reason, Dorian thinks it looks different this morning, as though there's a new cruelty in his painted twin's expression. He quickly checks to make sure he doesn't look like that; his actual face bears no such change.
Dorian remembers the rash wish he made in Basil's studio – he wished that the portrait could change and grow old, while he stayed the same. Could it be that his wish was granted?...
Looking at the portrait's new expression, Dorian starts to feel bad for poor Sibyl. He can't stop looking at the picture, and realizes that it will keep changing for the worse if he himself does. He draws a screen in front of the portrait, and tries to put it out of his mind, vowing to go back to Sibyl and marry her. Dorian, certain that his love for her will return, feels like everything will be all right.