The old man at the Eirtola house warns the new maid Eriikka about the fate of Jenny, the summer girl. Jouko, a university student from Eirtola, arrives home for the summer and begins to court the pretty maid. At the cattle shed, Eriikka finds a box, the contents of which she examines together with Pastor Tuomo Ahomaa. The tragic fate of Jenny, the summer girl, is revealed.
Unfortunately the movie Suviyön salaisuus is not yet available on Disney Plus.
| Writing | Kaarina Viitainoja | Screenplay |
| Sound | Holger Wernbom | Sound |
| Sound | Väinö Haapalainen | Original Music Composer |
| Art | Eero Leväluoma | Production Design |
| Production | Theodor Luts | Producer |
| Production | Emil Viljanen | Producer |
| Directing | Eino Kari | Director |
| Writing | Aksella Luts | Screenplay |
| Writing | Erkki Uotila | Screenplay |
| Writing | Kaarina Viitainoja | Novel |
| Editing | Eino Kari | Editor |
| Camera | Auvo Mustonen | Director of Photography |
| Camera | Esko Töyri | Director of Photography |
