Tasked with finding a US informant who has gone missing in the village of Hai Trang, Sergeant Reese and Corporal Hanson lead their squad off into the Vietnamese jungle, but it isn't long before they get the sense that there's something different about this mission. They find Viet Cong corpses along the path, strangely mummified or desiccated, and the village of Hai Trang itself turns out to be a ghost town. There, they find just one survivor - a young girl named Lai Anh - who tells them that everyone in the village has been destroyed by the "Vietnam Black".
Heading back to base, they stumble across a Viet Cong tunnel system, which they feel compelled to investigate. Crawling into the darkness, the squad discovers that a nightmarish creature has made the tunnels its home. The Vietnam Black, a colossal centipede, covered in impenetrable black armour, loaded with a highly poisonous venom, and armed with scythe-like mandibles, has awoken. Now, Reese has to lead his squad back home, avoiding the North Vietnamese Army, the Viet Cong, the dangers of the jungle, and the Vietnam Black.