The Midnight Tour by Richard Laymon

For years morbid tourists have flocked to the Beast House, eager to see the infamous site of so many unspeakable atrocities, to hear tales of the beast said to prowl the hallways. They can listen to the audio tour on their headphones as they stroll from room to room, looking at the realistic recreations of the blood-drenched corpses...

But the audio tour only gives the sanitized version of the horrors of the Beast House. There are some facts too gruesome for the average thrill seekers. If you want the full story, you have to take the Midnight Tour, a very special event strictly limited to thirteen brave visitors. It begins at the stroke of midnight. You may not live to see it end.