Part 1[edit]
E3: You will arrive via the bottom truck. If you hop back inside, you will be transported back to the checkpoint at the bottom of the initial jungle path. When you hop out of the truck, you will see one man standing guard at the entrance. Two other trucks sit idle. The upper left truck contains rations. Because some items return when you leave a room and come back, you should visit this truck at least three times to max out your ration inventory. However, every time you leave the truck, the guard standing nearby will notice you. The truck in the upper right will transport you to the entrance of building 4, just above the desert. You certainly should not visit that area at this time. If you wait long enough, the guard will be relieved of duty, and begin to walk away from the entrance. You can wait until that time, or sneak up on him and attack him before he leaves. Then activate card 1 as you approach the door to gain access to D3 inside.
D3: The entrance of building 1 contains long rows of cars. There is one guard which initially walks down the right side of the room. If you're quick, you can run up to him and knock him out before he turns the corner and notices you. When the coast is clear, head north to C3, but don't enter along the right wall, or the guard in the next room will notice you.
C3: One guard patrols this room as well, and you are protected from detection by hiding behind the tanks. The door in the upper right corner can be opened with card 1. Inside is another guard who will notice you immediately. Knock him out when he rushes toward you, and then approach the desk to collect the gas mask. When you exit the room, the guard standing outside will also notice you immediately. Knock him out and then head west to C2, avoiding the backup security that appears.
C2: Other than the stationary tanks, this room will be empty. Your next goal is to cross immediately over to C1. However, you can explore D2 and D1 along the way if you wish. D2 to the south contains one guard, and D1 is an empty room like C2. Ultimately, you must visit C1 to the west.
C1: Three guards occupy this room, making it a little more difficult to get through undetected. Big Boss will call you on the transceiver and remind you that your mission is to infiltrate and avoid detection. No matter how hard you try not to get spotted, it is likely that one of the guards will notice you. Your goal should be to reach the upper left path to B1.
B1: Assuming you arrive along the left path, one of the two guards stationed there will likely notice you immediately. Run past them and head immediately north to A1. If you happened to visit the right path, do not proceed north: there is a pitfall in this room that is difficult to avoid, and cannot be walked around. You must return south to C1 and back up through the left path.
A1: One guard stands patrol in front of the elevator. You can use the crates for cover. If you wait long enough, he will be relieved from duty and walk away, leaving the elevator doors unguarded. However, before you approach the elevator doors, you should visit A2 to the east first.
A2: Three trucks sit in this room, facing south, along with a single guard patrolling the top of the room, and a door to the east which you cannot open yet. You can explore the interiors by entering from the north. Investigate the left truck to find your first fire-arm, a handgun. Though you now have a weapon, you still do not have ammo for it yet. The middle truck contains four soldiers who will not be pleased to see you if you enter, so avoid it. In addition, as soon as you leave the middle or right truck, the guard at the top will notice you immediately. The right truck contains a set of five land mines. Collect them and leave the truck.
Once you have gathered the handgun and land mines, return west to A1, wait for the guard to leave his post, and enter the elevator. Your only choice will be to ride the elevator up to the third floor.
Part 2[edit]
You should be returning to this floor after you have explored the third floor and gathered card 2.
A4: When you arrive back on this floor through the elevator, be careful not to get noticed by the guards that patrol either side of this room. No matter what you do, do not attempt to run between the crates, as a pitfall will open up. Approach the right guard and punch him out or shoot him, and then continue south to room B4.
B4: The three cameras that monitor this room make it difficult to stay hidden. While you can simply hug the wall beneath the left camera and avoid detection, another way to guarantee your safety is to make use of the cardboard box that you collected from the third floor. Hop into the blind spot of the top right camera behind some crates and activate the box. Remain still as the left camera sweeps past your position. After it passes you on its way back down, activate card 2 and approach the door on the left (be careful not to get caught by the camera on the right). You'll find another prisoner to rescue inside. He'll inform you that Gray Fox is contained in an isolated cell. Exit the room and head to the south to room C4, using the box to avoid detection, or hugging the left wall. The upper right camera is likely to detect you unless you move up as soon as you exit the room.
If you've rescued every prisoner in the walkthrough so far, you will also be promoted to the second class. This will be indicated by the second star added below your health meter. You will have a new health maximum (although your current health remains unchanged) and you will now be able to store more ammo and rations.
C4: Two guards patrol either side of the passage. Punch them out or avoid them altogether, and approach the doors on either side. The left door is opened with card 1, and it contains a prisoner who will tell you that the best way to find the isolated cell is to get caught by the enemy. The right door can be opened with card 2. Inside, you will find the sub machine gun sitting on the desk. This is another weapon that is affected by the silencer, but you'll need to find more ammo before you can use it since it uses different bullets from the handgun. Explore both rooms, and then head south to room D4.
D4: A single guard patrols this room. You can easily knock him out before he notices you. You will see a truck and two cars. Hop inside the back of the truck and head inside a little bit until an enemy appears behind you. He will order you not to move and place you under arrest. The next thing you know, you will find yourself in an isolated cell…