There was a cave, a convoluted spiral cavern, and I was at a gathering of people inside of it.
I somehow experienced a series of psychic flashes, like pictures on a museum wall, showing past gatherings that had occured in this cave. I was horrified to realize that a dark pattern surrounded this cave: the gatherings, always of random mixes of people who just found themselves drawn to this place at a specific time (as I had been), would eventually turn from the amusing chit-chat of strangers who find themselves spending some time together in a crowded space, to something rather more bacchanalian. And, in fact, I was aware that the crowd around me was starting to change, that people were starting to break up into little groups of two and three, moving closer together, pressing against each other. Then, looking back at the psychic images, I saw that each time, in the middle of the most out of control part of the gathering, one person-- there was always one person who had not managed to break off with one or two other people for the crazy sex-up-- would go homicidally insane, and the cave would provide a weapon, and that person would kill all the others in a vicious blood-drenched frenzy.
Looking around, I realized this party will go the same way. I worried for a moment that I was to be the loner, but there was actually some girl sort of rubbing against me so apparently I was "safe"... but then I saw the loner, across the cave, looking increasingly agitated.
And as soon as I saw him, he looked at me, and I guess the dark spirits of the cave decided that their cover was blown and they needed to get this show on the road, because from out of nowhere he suddenly produced a shotgun and I ran, pulled away from the girl and ran for the mouth of the cave as fast as I could, as behind me he began to shoot...