As Master Class begins, the house lights are still up. An accompanist seats himself at a piano, after which Maria enters, wearing expensive clothes. She announces that there is to be no applause, because everyone is there to work. She makes some remarks about music as a discipline and says that the singer must serve the composer. In the first of many anecdotes about her life, she tells how, during World War II, she used to walk to the conservatory and back every day, even though she had no proper shoes.
She calls for the house lights to be turned off, and addresses some remarks to the accompanist, telling him that all performers must have a distinctive appearance. The accompanist becomes the butt of her somewhat cruel humor, and she pays tribute to her own teacher, Elvira de Hidalgo.
The first student, a young soprano named Sophie de Palma, enters. Maria criticizes her appearance and tells her to get over her nerves. Sophie says she is going to sing an aria from La Sonnambula (The Sleepwalker), an opera by the Italian composer Bellini. It is a difficult aria in which the heroine, Amina, bemoans her loss of love.
After a bored stagehand brings out the footstool that Maria has requested, the accompanist plays the introduction to the aria, but Sophie only manages to sing the first word before Maria interrupts. She tells Sophie that she is not really listening to the music and shows her how to do it. Sophie tries again, but again Maria interrupts her after the first word. She tells the soprano that she is not feeling the true emotions of the character.
Following another interruption from the stagehand, who brings a cushion for Maria, Sophie sings again. Maria gives instructions as her student sings. Then Maria asks the singer to translate from the Italian, and Maria instructs her on the passion behind the words. She also draws her attention to the stage direction, which calls for the singer to fall on her knees, which Maria demonstrates. Then she talks Sophie through the emotions that are being expressed in the aria and berates Sophie for not having a pencil handy to take notes. Maria recalls that her teacher never had to ask her if she had a pencil and adds that that was during the war, when there were shortages of everything. Having a pencil meant going without an orange. She made notes on everything, so she could continue the tradition built up over centuries of opera. She berates Sophie for not knowing the names of all the great sopranos, such as Giudetta Pasta (1797–1865), Zinka Milanov (1906–89), Rosa Ponselle (1897–1981), and Lotte Lehmann (1888–1976).
Sophie begins to sing, and Maria hears in her mind her own performance as a recording of Maria Callas is played. Her mind goes back to her relationship with the wealthy Greek businessman Aristotle Onassis, whose companion she was for many years. As she reminisces, she imitates Onassis’s voice and his crude way of speaking. She has him say that he bought her with his wealth and that she gave him class, allowing him to acquire the respect that had not formerly been given to him. He tells her how wealthy he is and that she can have...