CHAPTER TITLES: 1. Out of the Clouds; 2. The Sinister Signal; 3. In Hostile Hands; 4. Desert Law; 5. Mid-Air; 6. The Crystal Prism; 7. Danger's Doorway; 8. Dropped from the Clouds; 9. The House on the Roof; 10. Trapped; 11. The Seething Pool; 12. The Whirling Menace; 13. At the Last Minute; 14. Liquid Fire; 15. The Last Raid.