Jules Verne's fantastic 19th century novel Mysterious Island provided the title and little else for this spectacular filmization. Lionel Barrymore plays an altruistic scientist who has built an underground city, hoping to use the modernistic devices he has installed to bring about world peace. But evil Slavic nobleman Montagu Love, whom Barrymore regards as a friend, has other plans. He kidnaps Barrymore's daughter and forces the kindly scientist to gear up his inventions to make war. With the help of hero Lloyd Hughes, and with the unexpected assistance of a race of duck-like underwater humanoids, Barrymore destroys his subterranean domain and foils the villain's plans--at the cost of his own life. Though essentially a silent film, Mysterious Island includes several well-integrated sound sequences; its highlight was a Technicolor submarine ride, which unfortunately exists only in black and white today. The 1961 version of Mysterious Island has absolutely nothing to do with the 1929 version beyond its claim (again) to be based on the Verne original.
by Hal Erickson synopsis