<P> That morning, the two managers lament Christine's disappearance, as well as series of notes they received from the Opera Ghost trying to blackmail them for his payment and ordering them on how to run the opera house . When Carlotta returns, she is furious to find a note sent to her saying if she sang as the countess in Il Muto that night instead of Christine, then disaster "beyond (their) imagination" would occur . Firmin and André ignore the ghost's warnings and give Carlotta the lead role . That night, the Phantom interrupts the performance and criticizes their failure to follow his orders . </P> <P> Carlotta continues to sing, but her voice croaks (as a result of the Phantom tampering with her throat spray) and the lead role is given to Christine . While the ballet is being performed, the Phantom, not realizing the performance change, encounters the chief stagehand Joseph Buquet and strangles him before hanging him from above, creating chaos . Christine flees to the roof with Raoul . She reveals to him that she has seen the Phantom's face and fears him, but also pities him because of his sadness . Raoul tells Christine he loves her and will protect her forevermore . Christine returns his love, kissing him passionately and they both leave the roof . The Phantom, who witnessed the scene, becomes heartbroken . He then hears them both singing together . Growing furious at Raoul, he vows revenge on them both . </P> <P> Three months later, a masquerade party ensues in the opera house . At the party, Christine wears her new engagement ring from Raoul . The event is interrupted once again by the Phantom, who is dressed as Red Death . The Phantom brings his own composition, Don Juan Triumphant, and orders the managers to stage the opera . Raoul exits the room and Christine approaches the Phantom . At the sight of the engagement ring, the Phantom rips it from Christine and disappears into a trap on the floor . Raoul tries to follow him but is stopped by Madame Giry, who privately tells him the story of the Phantom's past . When she was a little girl, she went to a freak circus where they featured a deformed child in a cage . The child was beaten while everyone watched and laughed . The ringmaster then removed a burlap sack covering the child's face, revealing his deformity . Only the young Madame Giry pitied him . She was the last to leave and saw the child strangle the ringmaster with a rope . Chased by the police, Madame Giry helped him escape and found shelter for him beneath the opera house, where she has hidden him from the world ever since . </P> <P> Christine takes a carriage to visit her father's grave, but the Phantom secretly takes over the reins . Raoul follows when he realizes she's gone . Christine arrives and laments over her father's death . The Phantom tries to win her back by pretending to be her father's angel, but Raoul arrives and stops him . A sword fight ensues in the cemetery, where Raoul eventually disarms the Phantom and is about to kill him, but Christine pleads for him not to . His rage seemingly augmented, the Phantom watches angrily as Christine and Raoul ride away . </P>

Who sang for christine in phantom of the opera