Ambitious Helen Chernin (Ida Lupino) pushes her talented younger sister Katherine (Joan Leslie) into marriage with broken down song-and-dance man Albert Runkel (Jack Carson) so that the two women can leave the dirty steel town where they live. Runkel's partner Paul Collins (Dennis Morgan), however, sees through Helen's plan. Helen continues driving her sister's career and eventually Katherine becomes a star on Broadway, while Runkel and Collins' act flounders. Success soon goes to Katherine's head and she becomes a fast-living party girl. Time passes and Helen and Katherine run into Paul, now a successful band leader. He and Katherine soon fall in love. The two sisters eventually have a showdown on opening night of Katherine's latest show when Katherine discovers that Helen is also in love with Paul.