City of Earthfire: Echoes from the Abyss

Lu Yan, a geology graduate student, accidentally stumbles into a mysterious sinkhole sealed off by the military while investigating clues surrounding his advisor's bizarre disappearance. During a cave-in, he is parasitized by a black obsidian crystal that fell from the rock strata and pulses like a heart. From then on, he gains the ability to hear the “memories” of all things: [Echoes of the Abyss].

The crystal is a legacy left behind by an ancient “Earthfire Civilization” that vanished in prehistoric times. They were not simply an ancient people, but “pioneers” who mastered geological energy and biotechnology. To escape an apocalyptic catastrophe from outer space, they moved their entire civilization beneath the Earth's surface and used unimaginable technology to create an underground world sustained by geothermal energy and a unique ecological cycle.

His advisor's disappearance is connected to this underground world. To find his mentor and unravel the mystery of the changes taking place within him, Lu Yan assembles a temporary expedition team: a retired female soldier with exceptional combat skills who handles security, and a “theory-minded” friend well versed in paleontology and mythology. Following the fragmented “voices” provided by [Echoes of the Abyss], they embark on a one-way journey toward the Earth's core.

In this bizarre underground kingdom that overturns every scientific principle, they will face more than just mutated behemoths that crave light and floating temples riddled with ancient mechanisms. A mysterious organization is also coveting the legacy of the “Earthfire Civilization.”