During its long retreat from Philadelphia, the First Battalion under Lt. Colonel Lee reaches the secret government facility at Mount Weather. Lee immediately secures the fort around the operations center, but then he learns of an outbreak of the plague in the bunker facilities below, where the U.S. government has taken refuge. The President herself has been infected. While thousands of infected clowns besiege the refuge outside the complex, Sergeant Muldoon, Corporal Rawlings, and a platoon of Lightfighters push into the underground tunnels of the facility. Their mission is to kill the President of the United States.