From the introduction:
During the Vietnam War the Vietcong were known to attack from one direction, vanish, and reappear in another. After an encounter, no matter how sure a kill the bodies vanished. No matter how well prepared your defenses they would appear inside. Nobody was safe against a seemingly supernatural threat.
But later in the war, underground tunnel networks were discovered. Places where the Vietcong could hide and ways traverse the battlefield without risk of discoveries. These tunnels contained everything from natural bunker firing positions to hospitals for their wounded. They would even drag their dead into these tunnels so that the American’s wouldn’t being able to track causalities, and in one case even buried an American tank.
But those that tried to enter the tunnels came face to face with threat of booby traps, wild animals, enemy combatants and the claustrophobia of maneuvering through such a tiny space.
This is where the Tunnel Rats come in. A pure volunteer set of men from Australia, New Zealand and the United States willing to make their way inside the tunnels, secure any valuable intel, eliminate any enemy forces and destroy the tunnels from within.
Faced with one of the highest mortality rates of any enlisted soldier in the war and stresses that can break a human being do you have what it takes you survive?