| # | Book Title | Author | |
|---|---|---|---|
| 1 | Mystery at Johnson Farm | Stahl, Hilda | |
| 2 | Secret Box, The | Stahl, Hilda | |
| 3 | Disappearance, The | Stahl, Hilda | |
| 4 | Dangerous Double, The | Stahl, Hilda | |
| 5 | Secret of the Gold Charm | Stahl, Hilda | |
| 6 | Fugitive, The | Stahl, Hilda | |
| 7 | Trouble at Sandhill Ranch | Stahl, Hilda | |
| 8 | Mystery of the Hidden Key | Stahl, Hilda | |
| 9 | Uninvited Guests, The | Stahl, Hilda | |
| 10 | Unexpected Letter, The | Stahl, Hilda | |
| 11 | Hiding Out | Stahl, Hilda | |
| 12 | Trouble From the Past | Stahl, Hilda |