The Great Radium Mystery: Criminals steal a radium-powered tank from an inventor. His heiress and a government agent take up the chase. 18 episode serial-1. The Mystic Stone, 2. The Death Trap, 3. The Fatal Ride, 4. The Swing for Life, 5. The Torture Chamber, 6. The Tunnel of Doom, 7. A Flash in the Dark, 8. In the Clutches of a Mad Man, 9. The Roaring Volcano, 10. Creeping Flames, 11. Perils of Doom, 12. Shackled, 13. The Scalding Pit, 14. Hemmed In, 15. The Flaming Arrow, 16. Over the Cataract, 17. The Wheels of Death, 18. Liquid Flames.