Ignoring the adoration of Billy, a shy, sensitive young man, Trilby O'Ferral falls under the spell of Svengali, the sinister hypnotist. She and Svengali develop a concert act and tour successfully, forsaking Trilby's former friends. But Billy's love is unwavering and wins out at last over the dark power of Svengali. A last-minute replacement for the equally flamboyant Robert Newton, Wolfit pulls out all the stops as the scroungy, sinister musician/mesmerist who hypnotizes lovely artist's model Trilby (Hildegarde Neff) and transforms her into a world-famous singer. While under Svengali's spell, Trilby forgets all about "Little" Billy (Terence Morgan) the starving artist who loves her fervently. But Billy doesn't forget, and follows Svengali and Trilby all over the world.