After a few minutes, they came to a place where the tunnel terminated in a rock wall pierced by a mouse hole just big enough for Chet to walk upright. "See, this thing was an adit," Chet was explaining, "which is what the miners call a tunnel that runs horizontal, flat enough that you can run rail cars on it. Straight into the ore body in the heart of the mountain. Only this first part of it, here, got expanded for the railway. But now we’re going into the adit proper." There was another pileup of trash and another steel door, barring the entrance to the adit, that had been jimmied open and left hanging askew. It would have been a natural place to put another booby trap. But Zula did not see or smell spray paint, and Chet’s minute inspection of the trash and the door revealed nothing suspicious. They stepped into the much more confined space of the adit and discovered that, as always, revelers and graffitists had been there first.