On the Edge of the Sword

Maxim learns of an ancient legend about treasures hidden by pirates on the Russian Baltic island of Gogland. Along with his friends, he goes to the island during summer vacation in hopes of using his own method to find the pirates' wealth. From time to time, their paths cross with two German scientists conducting what they described as geological explorations… One night, the kids notice some suspiciously mysterious guests with the scientists. Who are these people? And why are they hiding in the night?..