Boris Karloff's first film.
Chapter titles: 1. The Ebony Block. 2. The Counterplot. 3. Underworld Terrors. 4. Through Doors of Steel. 5. The Brass Key. 6. The Mystic Box. 7. Meshes of Evil. 8. Cave of Dread. 9. Falsely Accused. 10. The Baited Trap. 11. The Bars of Death. 12. Hurled into Space. 13. The White Roses. 14. Cleared of Guilt. 15. Wu Fang Atones.