A variety of people are searching for a long-hidden treasure somewhere on an island. Chapters: 1. The Isle of Fear, 2. The Ghost Talks, 3. The Phantom Duel, 4. Buried Alive, 5. The Girl Who Vanished, 6. Trapped by the Flood, 7. The Cannon Roars, 8. The Circle of Death, 9. The Pirate's Revenge, 10. The Crash, 11. Dynamite, 12. The Bridge of Doom, 13. The Mad Flight, 14. The Jaws of Destruction, 15. Justice
Don Terry
as Larry Kent
Gwen Gaze
as Toni Morrell
Walter Miller
as Carter 'The Shark' Collins
George Rosener
as Capt. Samuel Cuttle
Grant Withers
as Roderick Gridley
Hobart Bosworth
as Dr. X
Sandra Karina
as Nurse Zanya
P.J. Kelly
as Prof. Gault
Yakima Canutt
as Dreer (Mole-Men Leader)
William Farnum
as George Brennan Westmore (Editor)
Joe Caits
as Saltwater Jerry [Chs.1,4-7,13-15]
Colin Campbell
as Hawkins (the Butler) [Chs. 1-3]
