The dacha where the legendary detective, retired Colonel Matveich lived, stood on the shore of the large White Lake, over which fog swirled and seagulls flew. The beauty was indescribable... Only Dimka and Alyoshka managed to find adventures here too! It all started when big-eyed Leshka noticed a yellow light in the distance behind a small forest. There was an abandoned quarry there, where Matveich strictly forbade them to go. Alyoshka immediately decided that normal people would not start a fire in such a place. There must be some terrible secret hidden here. The near future showed: he was not mistaken...