The mine had shut down many years ago. The last people to have had a good reason to go down into those tunnels would have been your grandfathers' age, but of course that didn't stop the youth from occasionally venturing down into the darkness to party or get alone time with a young lover.
Normally, it was okay. The mine shaft was quite drafty and very dark, but if you were okay with a few broken beer bottles, it was a good place to find peace and quiet.
Except for when the sky was dark.
No one went into the tunnels on the new moon. Because when the moon wasn't visible in the sky, something bad always happened. The authorities would repeat the same stories: a tragic accident, must have been an animal attack.
But those who found the bodies swore that it was no animal that did this. Those who discovered the massacred flesh of those poor lost souls never went down in the mine shafts again, too terrified that they would be the next ones to have their skin flayed clean off and their meaty flesh consumed.