| # | Book Title | Author | ||
|---|---|---|---|---|
| 1 | Secret of Terror Castle, The | Arthur, Robert | ||
| 2 | Mystery of the Stuttering Parrot, The | Arthur, Robert | ||
| 3 | Mystery of the Whispering Mummy, The | Arthur, Robert | ||
| 4 | Mystery of the Green Ghost, The | Arthur, Robert | ||
| 5 | Mystery of the Vanishing Treasure, The | Arthur, Robert | ||
| 6 | Secret of Skeleton Island, The | Arthur, Robert | ||
| 7 | Mystery of the Fiery Eye, The | Arthur, Robert | ||
| 8 | Mystery of the Silver Spider, The | Arthur, Robert | ||
| 9 | Mystery of the Screaming Clock, The | Arthur, Robert | ||
| 10 | Mystery of the Moaning Cave, The | Arthur, Robert | ||
| 11 | Mystery of the Talking Skull, The | Arthur, Robert |