Trilby

Trilby is tone-deaf: "Svengali would test her ear, as he called it, and strike the C in the middle and then the F just above, and ask which was the highest; and she would declare they were both exactly the same."
Svengali hypnotizes her and transforms her into a diva, la Svengali. Under his spell, Trilby becomes a talented singer, performing always in an amnesiac trance. At a performance in London, Svengali is stricken with a heart attack and is unable to induce the trance. Trilby is unable to sing in tune and is subjected to "laughter, hoots, hisses, cat-calls, cock-crows." Not having been hypnotized, she is baffled and though she can remember living and traveling with Svengali, she cannot remember anything of her singing career.