"It's a pattern. This is where they've hidden their secret."
"It looks more like the place a co-ed and her boy friend might go to have a little fun. In warmer weather, of course."
"Oh!" she said. "You're disgusting! Look over there."
He looked, wondering what made this young attractive woman hypersensitive on the subject of sex. This was the second time she'd blazed up over nothing. What he saw where she pointed was a door at a 45-degree angle to the ground, set into a triangular block of concrete. "Where does that go?" he asked.
"Down," she said as they walked toward it. "And there's some machinery or something down there. I heard it. Or maybe I only felt the vibrations. It throbs, anyway."
"Probably the generator for the school's lighting system. Did you go down and look?"
"No."
"All right, then." He opened the door. "Down we go."
At the bottom of a flight of steps there was a corridor lit by dim electric light bulbs along one wall. The corridor became a tunnel, sloping gradually downward. They had been going north, Don judged, but then the tunnel made a right turn and now they were following it due east. "I don't hear any throbbing," he said.
"Well, I did, and from way up here. They must have turned it off."