A few days later, rookie operative Solid Snake was called in for his first assignment for FOXHOUND. His commanding officer, Big Boss, briefed him on the situation, and after handing him a classified document detailing Gray Fox's infiltration route, ordered Solid Snake to perform a follow up mission entitled Operation Intrude N313. His mission objectives were to rescue Fox, and to find out the truth behind Metal Gear. After dispatching him to the rough area of Outer Heaven's location, Big Boss contacted Snake via his wireless radio and reminded him that what he was about to experience is nothing like what he has experienced in battle before.
Snake infiltrated Outer Heaven via an underwater insertion, and proceeded into the base, eventually managing to locate Fox with intel provided by Outer Heaven's prisoners and the Resistance leader Kyle Schneider. To get there, Snake allowed himself to be captured, and then after being thrown into a prison with all his weapons and equipment confiscated, he managed to break through a weakened wall under Big Boss's advice to get to Fox's cell next door. Gray Fox then revealed to Snake the true meaning behind Metal Gear: a walking battle tank capable of launching a nuclear missile from any kind of terrain. Luckily it was still in a hangar within the fortress and had not yet been activated. Fox told Snake to find Dr. Drago Pettrovich Madnar, the creator of Metal Gear and the only person who knew how to destroy it, explaining that he should be in a prison cell at the courtyard. After breaking out of the cell, he ended up encountering the prison's warden, Shotmaker, who attacked Snake while declaring that no one had ever escaped from the prison. Snake was forced to retreat into an unlocked room due to not being able to attack Shotmaker without his equipment. After retrieving his confiscated belongings, as well as getting rid of a transmitter that was planted among his belongings, he then managed to fight Shotmaker.
