[Part 1] Deep in the majestic, mist-shrouded Hundred Thousand Mountains in southwest China, a modern biomedical research institute code-named "Panlong" quietly stands. It belongs to the powerful "Panshi" business empire. Its surface facilities are bright and advanced. Underground, it secretly transformed and utilized the huge "Longyuan" underground fortifications left over from the Cold War, and conducted top-secret research - the exploration of an ancient symbiote "Ouroboros Symbiote-OS" discovered in the extremely deep strata of the Qinghai-Tibet Plateau.
The disaster spread quickly. The luxury high-speed train "Huanshan" passing through the mountainous area near "Panlong" encountered strange spore clouds or leaked parasites in the mountain tunnel. Passengers and flight attendants mutated into terrifying monsters in the closed carriage. At the same time, the surface part of the "Panlong" Research Institute also turned into hell, the security system failed, and the staff devoured each other or deformed in despair.
The "Panshi" Group immediately initiated the cover-up program and dispatched ruthless and efficient "Scavenger" troops. The mission goal was to recover core data samples and eliminate all sources of infection and witnesses - dead or alive. The gears of fate turned. Lin Feng, a criminal police officer who was suspended from duty to pursue clues, and Su Jin, a researcher who was ordered to verify biological threats, boarded the "Huanshan" train to hell without knowing it. When the train came to an abrupt stop in the tunnel, the lights went out, and horrifying howls sounded, their path to survival and the journey to uncover the dark truth of the "Coiling Dragon" were forced to unfold in flesh and blood and despair. The closed loop has just begun.
