Two youngsters vacationing at the Black Sea sneak onto a mysterious ship and spy the peculiar activities of a treasure-seeking crew. They are discovered and imprisoned as the ship heads for an uncharted island. Their parents put together an expedition and after numerous adventures the treasure hunters are apprehended and the mystery of a secret cove is solved.
| Writing | Kazimierz Tarnas | Writer |
| Writing | Leslaw Bartelski | Novel |
| Directing | Kazimierz Tarnas | Director |
| Production | Tadeusz Lampka | Production Manager |