The Nalenggele Gorge in the middle section of Kunlun is a strictly prohibited, uninhabited restricted area. Within the gorge, the Netherworld Cave is perpetually swept by cold winds and infested with venomous insects; throughout the ages, countless explorers who ventured inside have never returned. In the early days of the People's Republic, over two hundred personnel pursuing remaining bandits entered the gorge and vanished in a strange manner, leaving behind an unsolved mystery. This place can only be entered during a brief window spanning the transition from winter to spring; it is also rife with legends of the Tuyuhun royal family's treasure and the hidden hoards of the Ma clique. In the early 21st century, an archaeological team successfully located the Tuyuhun burial site, and the treasure rumors appeared to be laid to rest. Yet when a second group of archaeologists stepped into the gorge, the entire team abruptly lost contact. Authorities have regrouped — and now, will yet another scientific expedition be able to uncover the secret hidden within the cave?