This is the site of a number of caves in the northern parts of the Caucasus. Local lore informs us that a monster lives in the caves, but the locals seem to have no inkling of what it looks like. Its existence seems to be inferred from the fact that both people and animals have disappeared in the vicinity. Whether there was a tradition of a monster anterior to these disappearances, I cannot say.
Under the Soviet régime, it was decided to build a military center in the caves. In 1949 a party sent into them returned unscathed, but then a second party was sent in. It did not return. An investigation was carried out. One member of the party, or rather most of him, was found dead. The head had been removed. A second member was also found dead. He had had the flesh removed from his bones. The authorities decided somewhere else might be a more suitable locale for their center.
This is all the information I have about this site and this incident. I would welcome further information on the matter.
Not knowing what the Monster looks like, I have put in this question mark as an illustration.