In young Lily Garland, Broadway impresario producer Oscar Jaffe sees the next big star, a view not shared by others. However, Jaffe does end up coaxing out of the naive young woman a great Broadway actress. Jaffe mentors her to one Broadway success after another, to a point where Garland is as big a Broadway name as he is, with the same difficult temperament to boot. She ultimately sees their professional and personal relationship as being Svengali-like, to which she rebels and runs off to movie stardom in Hollywood. Without Garland, Jaffe's career declines. By happenstance however, both Jaffe and Garland end up on the same Twentieth Century train back to New York. Jaffe takes this opportunity to try and lure his protégée back under his wing on Broadway, but Garland has other thoughts on her mind, basically anything but Jaffe. However, Jaffe figures a good part and a few acting chops of his own might be able to persuade Garland that she should return to her life with Jaffe. A lunatic let loose on board the Twentieth Century adds a few complications to the proceedings.