C616 Ignored clues

Before they could even get close, a guard stopped Xia Lei and Fan Fan Fan from entering. Xia Lei and Fan Xian walked forward for a distance before they saw an entrance. It was a man-made tunnel, paved with gravel that slanted downwards. At the end of the passageway was an arched stone door. The stone door had already been opened, and a paved passageway extended underground