A music master mesmerizes a young model into becoming his wife and a concert singer in this adaptation of George Du Maurier's novel Trilby.
In Paris Svengali (John Barrymore) is giving a singing lesson to a woman, who has just left her husband for him. Svengali asks her what her husband left her. When he discovers she came to him with no settlement at all, he gazes at her intently until she departs in terror. His servant Gecko tells him that her body was found dead in the river and that they need the rent money. Svengali and Gecko call on two English painters who are taking a bath. They throw the Polish music master in the bath and take his clothes; but Svengali puts on Taffy's best suit and departs with the money hidden in the pocket.
At the artist's studio Svengali meets a pretty model named Trilby O'Farrell (Marian Marsh) and discovers she has a fine singing voice. Trilby gets to know the painters and says yes to young Billee (Bramwell Fletcher). She tells Svengali she has a headache, and he takes it away by hypnotizing her. Soon Billee gets a letter from Trilby saying he will never see her again. Police have found her clothes on the banks of the Seine.
Five years later Madam Svengali is receiving great applause on her concert tour of Europe. The three English painters are turned away from the stage door, but Billee sees Trilby coming out. She greets him happily until Svengali gives her the eye; then she tells Billee he was mistaken. Trilby thanks Svengali, but he says that she does not love him. After he hypnotizes her, she does say that she loves him; but he knows it is only another part of himself. Billee goes after the Svengalis, and Svengali cancels one performance after another, saying he is sick until they can no longer get a concert in Europe.
Trilby is to appear with dancing girls in an Egyptian cafe, and Svengali almost cancels again; but he tells Billee this is going to be Trilby's last concert. He hypnotizes her; but during the concert he collapses, and then she does too. Svengali asks to have the woman in death he could not have in life, and they both die.
This story shows the mutual dependence of a domineering personality over a submissive one. Svengali can control Trilby, but in that control he cannot experience her own love. Having taken her love for Billee away from her, he is left with nothing but his own psychic power and death.