Based on the Robert Louis Stevenson story: Doctor Henry Jekyll's enthusiasm for science and his selfless acts of service have made him a much-admired man.
But as he visits Sir George Carew one evening, his host criticizes him for his reluctance to experience the more sensual side of life. Sir George goads Jekyll into visiting a music hall, where he watches the alluring dancer Gina.
Jekyll becomes fascinated with the two contrasting sides of human nature, and he becomes obsessed with the idea of separating them. After extensive work in his laboratory, he devises a formula that does indeed allow him to alternate between two completely different personalities, his own and that of a brutish, lascivious person whom he names Hyde.
It is not long before the personality of Hyde begins to dominate Jekyll's affairs.
* Many adaptations of the Robert Louis Stevenson's novelette were written as plays and performed; the earliest in the United States by Thomas Russell Sullivan opened in Boston on 9 May 1887 and moved to New York City on 12 May 1887.
* In the short Renaissance flashback memory sequence, where Hyde is explaining to Gina about the poisonous mysteries of his secret ring, set pieces and costumes were brought from "The Jest". That was a hit play in which John Barrymore had starred with brother Lionel Barrymore on Broadway in 1919 before shooting this picture.
* John Barrymore hauled many of his prized potted plants from his apartment to the set to appear in scenery in the movie.
* This was one of the first major productions filmed in Paramount's then new Astoria Long Island studios. Opened in 1919 the studios underwent a major soundproofing renovation when talkies arrived in 1929.
John Barrymore ... Dr. Henry Jekyll / Mr. Edward Hyde
Charles Lane ... Dr. Richard Lanyon
Brandon Hurst ... Sir George Carew
Cecil Clovelly ... Edward Enfield
Nita Naldi ... Miss Gina - Italian Singer