A guard blocked Xia Lei and Fan Fan off before they could get close to their destination. Fan Fan showed her ID and was allowed to go through, together with Xia Lei. Xia Lei and Fan Fan walked forwards for a bit more before they saw an entrance. It was a passageway that that a worker had cut, slanting and extending underground, with crushed stone spread out around it. An arching stone door was at the end of the passageway. The stone door had already been opened, and another rock-covered passageway extended downwards. Some lamps had been lit in the passageway, but there were several curves and corners, so they couldn’t see the end in a glance.

“I came with my grandfather three times but we didn’t discover anything at all,” said Fan Fan when they entered the passageway behind the stone door. Her voice echoed in the passageway along with the clicking sounds of her high heels, going into the depths of the passageway.

“Did you guys go to the unopened areas too?” asked Xia Lei. 

“No,” said Fan Fan. “Some of the unopened areas are buried in soil, and water has seeped through in some areas so you can’t...