1. The Secret of Terror Castle (1964) by Robert Arthur
2. The Mystery of the Stuttering Parrot (1964) by Robert Arthur
3. The Mystery of the Whispering Mummy (1965) by Robert Arthur
4. The Mystery of the Green Ghost (1965) by Robert Arthur
5. The Mystery of the Vanishing Treasure (1966) by Robert Arthur
6. The Secret of Skeleton Island (1966) by Robert Arthur
7. The Mystery of the Fiery Eye (1967) by Robert Arthur
8. The Mystery of the Silver Spider (1967) by Robert Arthur
9. The Mystery of the Screaming Clock (1968) by Robert Arthur
10. The Mystery of the Moaning Cave (1968) by William Arden
11. The Mystery of the Talking Skull (1969) by Robert Arthur
12. The Mystery of the Laughing Shadow (1969) by William Arden
13. The Secret of the Crooked Cat (1970) by William Arden
14. The Mystery of the Coughing Dragon (1970) by Nick West
15. The Mystery of the Flaming Footprints (1971) by M V Carey
16. The Mystery of the Nervous Lion (1971) by Nick West
17. The Mystery of the Singing Serpent (1971) by M V Carey
18. The Mystery of the Shrinking House (1972) by William Arden
19. The Secret of Phantom Lake (1972) by William Arden
20. The Mystery of Monster Mountain (1972) by M V Carey
21. The Secret of the Haunted Mirror (1972) by M V Carey
22. The Mystery of the Dead Man's Riddle (1972) by William Arden
23. The Mystery of the Invisible Dog (1973) by M V Carey
24. The Mystery of Death Trap Mine (1976) by M V Carey
25. The Mystery of the Dancing Devil (1976) by William Arden
26. The Mystery of the Headless Horse (1977) by William Arden
27. The Mystery of the Magic Circle (1977) by M V Carey
28. The Mystery of the Deadly Double (1978) by William Arden
29. The Mystery of the Sinister Scarecrow (1979) by M V Carey
30. The Secret of Shark Reef (1979) by William Arden
31. The Mystery of the Scar-Faced Beggar (1981) by M V Carey
32. The Mystery of the Blazing Cliffs (1981) by M V Carey
33. The Mystery of the Purple Pirate (1982) by William Arden
34. Mystery of the Wandering Cave Man (1982) by M V Carey
35. The Mystery of the Kidnapped Whale (1982) by Marc Brandel
36. The Mystery of the Missing Mermaid (1983) by M V Carey
37. The Mystery of the Two-Toed Pigeon (1983) by M V Carey
38. The Mystery of the Smashing Glass (1984) by William Arden
39. The Mystery of the Trail of Terror (1984) by M V Carey
The Case of the Dancing Dinosaur (1985) by Rose Estes
40. The Mystery of the Rogues' Reunion (1985) by M V Carey
41. The Mystery of the Creep-Show Crooks (1985) by M V Carey
42. The Mystery of Wreckers' Rock (1986) by William Arden
43. The Mystery of the Cranky Collector (1987) by M V Carey