1942, North China Plain. Han Geng, a militia captain who was a surveyor and mapping soldier, was forced into a desperate situation by the Japanese army. He accidentally activated the "tunnel map system" - he could turn the land under his feet into a three-dimensional map, displaying the tunnel network, enemy positions, landslide risks in real time, and even deducing the optimal excavation route.
But the system has limitations: it needs to rely on villagers' labor and "engineering points" captured on the battlefield to upgrade. Han Geng led the whole village, young and old, starting from a hiding hole and gradually digging out an underground Great Wall that connected eight villages and spanned fifty miles. They used the early warning, navigation, and trap marking functions of the map system to smash the Japanese ground-penetrating radar, poison gas attacks, and special attack team infiltrations time and time again.
This is not a heroic story of one person, but a victory for every ordinary person who dug soil, delivered meals, and reported news under the tunnel network. When the Japanese army brought in heavy artillery and engineering units in an attempt to destroy the tunnels, Han Geng saw the only counterattack path on the system map - to penetrate directly into the enemy's headquarters from the ground.
Tunnels can not only hide, but also attack.
