The Secret Kingdom is a 1917 silent action movie serial comprised of 15 chapters: 1. Land of the Intrigue 2. Royalty at Red Wing 3. Sealed Packet 4. Honorable Mr. Oxenham 5. Carriage Call #101 6. Human Flotsam 7. Ghost Ship 8. Rum Cay 9. Swamp Adder 10. A Goat Without Horns 11. The White Witch 12. The Shark's Nest 13. The Tragic Masque 14. The Portrait of a King 15. The Tocsin.

• Star Film Company
• Vitagraph Company of America
• Charles Richman
• Dorothy Kelly
• Joseph Kilgour
• Arline Pretty
• William R. Dunn
• De Jalma West