Wu Xie gets pulled back into the mountains because a ghost of a friendship won't let him stay buried, and this time the thing waiting for him isn't just another tomb, it's something older than tombs. The show trades the claustrophobic puzzle-box plotting of earlier chapters for something stranger: vast underground spaces that feel like they're watching you back. It knows the real horror isn't what's hiding in the dark, it's standing in front of something so ancient and patient that your entire life is just a blink to it.

Back in Hangzhou after two earlier adventures in Nansha, Wu Xie gets an unexpected call from Lao Yang, a childhood friend he has not seen in a long time. Lao Yang brings up an adventure the two shared in the remote Qinling Mountains three years ago and asks Wu Xie to go back with him to explore the ancient ruins there. On the expedition they come across an enormous taimen, a vast waterfall hidden underground, and a mysterious sacred tree of great age. All the while, the ever elusive Zhang Qiling is quietly helping Wu Xie from behind the scenes. The twelve-episode ONA mixes adventure, mystery and the supernatural.