When you resume, jump the railing, maneuver along the ledge and climb into the first window on the left. Snag the letter off the table and then get back to the ledge. Continue along until you drop onto a roof, then climb down through the hatch. Go through the door in front of you and turn left to find the battery you'll need to operate the Laser Cutter. Head back the way you came and up the stairs to find a place you can charge the battery. Use the Laser Cutter to cut a hole in the fence and sneak through.
Tip: Keep the Laser Cutter charged at all times. Even if you don't think you need to, stop at every charge station and fill it up. Even consider backtracking to charge it, just to be sure.
Jump from the window to land on the nearby roof. Let the guard pass, then open one of the windows to sneak behind him for the Knife kill. Note the Signal Detected on your screen before carefully sneaking behind the three guards in the next room and taking them down with stealth. You want to be very quiet here so as not to alarm the Kampfhund sleeping nearby. When the last guard is down, crouch and move toward that monstrous excuse of a dog, putting your Knife in the beast before he wakes up.
Search the main room for a file, picking it up and putting it in the filing cabinet to trigger a secret door. As soon as the phone rings, answer it and wait for the conversation to end. Head into the secret door in between the cabinets and loot the room. When you're done, backtrack into the control room and head to the opposite end and up the stairs.
When you reach the office, sneak up behind the Commander and put a Knife in his head. Loot the room, head outside and follow the ledge all the way around the waiting transport. Jump on top of it, triggering a cut scene and progressing the mission.
Immediately head up the stairs and follow the catwalk around to a ladder. Climb it and keep moving to a second ladder, climbing it as well. Once on the roof, you should see a lone guard with his back to you. Be sure to crouch, sneaking up behind him for the stealth takedown. Use the Laser Cutter to break through the chain holding the gate shut, then drop down to the ground level.
Be sure to charge your Laser Cutter again before moving on, then sneak up behind the next guard to put him down with another stealth kill.
Tip: Look for doors with motion lasers on them. Don't walk into their path, and if you do, shoot them or they will engage and try to kill you.
Cut through both sets of fences in order to access the interior of the courtyard. Head to the side opposite of where you started, then climb into a vent that leads to the prison's interior. As soon as you're inside, watch out for the giant death robot trying to kill you. Run away from him and slide under the wall before he swats you, then use your Laser Cutter to drop through the grate in the floor. Follow the tunnel until you see a guard standing at the end. Wait for him to approach and knife him.
Continue along the tunnel up a ladder. Sneak into a bathroom and kill the urinating guard in one of the most horrible ways possible. Exit the bathroom and sneak through the halls, killing the Kampfhund taking a nap nearby. Head into the sleeping quarters, first knifing the guard in the chair and then the one sleeping on the top bunk. Loot the room, making sure to pick up the key hanging on the wall in the box next to the first guard's chair.
Exit the room and continue down the hall (past where the Kampfhund was sleeping), taking the open door on your left. Sneak up on the Commander and do what you do, you lethal Nazi killer you. Be sure to use the charge kit for your Laser Cutter, then snag all the goodies laying around before exiting the room and heading on your way. Use the key you picked up from the sleeping quarters to unlock the door near the end of the hall.
Tip: The Lower level of the catwalks are patrolled by a lone guard, but contain a Laser Cutter Upgrade: Shooting. No matter what approach you take, don't miss out on picking this up.
As soon as you open the next door, you'll be behind a guard patrolling along the catwalks. We decided to follow him, killing him when we caught up. This put us on the ground floor where we also found a few items worth looting. However, you could opt to turn left on the catwalk (instead of following the guard), and head to the chained door at the other end. Whichever option you choose, make sure to make a stop to snag the Laser Cutter Upgrade before cutting the chain off the door and moving on.
After moving through the door, the papa death robot dog is back. It looks like he can't reach you, but he can. Just sprint along the catwalk and use your Laser Cutter to cut the chains and move to the next area. If you're out of juice, there's a charge kit on the wall just before you reach the chains.
Once you reach the cell block, sneak forward into the guard station and Knife the guard in the back. The other one will see you, but just attack him and take him out. Check the area for pickups before you hop on the elevator and take a ride up toward your destination.
As soon as you enter cell B2, have a brief but brutal fight with the guard, then use your Laser Cutter and free all the prisoners. Take a brief moment to charge it up on the wall before removing the helmet from the prisoner shouting at you.
Jump on top of the table that the prisoners have wedged against the door and use your Laser Cutter to open the hatch. Climb inside and crawl to the other end, dropping into a room behind a Commander. He looks like he needs a Knife to the head... don't let him down. This room is the jackpot of gear. Clean out all the weapons, armor and health that you can find, then pull the lever by the door.
Tip: Before leaving the room, grab the Automatic Shotgun from the floor. This thing is like bowling with Hand Grenades. Enjoy.
You'll now be right behind the guards trying to kill Fergus. It's a great opportunity to use your wonderful new toy, but we decided to Knife them all in the back. Once you're teamed up with Fergus again, get ready to go to work.
Follow Fergus into the next room, hitting the button when he gives you the word. Crawl under the door and move the only direction you can. Watch out for the automatic turrets; they can do some damage if you don't take them out quickly. Since your goal is to reach the ground floor, keep moving until you flip the switch, then jump down into the water and follow Fergus out the door.
As soon as Fergus opens the gate, shoot the prone Nazi and you'll be back in the same courtyard where you cut the two holes in the fences. They know you're here, so the strategy is to move, shoot and reload until everyone and everything is dead. Make sure to loot any side rooms, and be especially careful of the heavily armored bad guys. They go down like all the rest; it just takes a few extra shots.
Continue to follow Fergus until you find yourself in some narrow hallways filled with Nazis. This is a good place to use your Hand Grenades, but even if you just go crazy with the Automatic Shotgun, you're not going to find much opposition here. Once the area is clear, grab all the pickups in the main control room and then move up a couple flights of stairs.
The top of the stairs will have several heavily armored soldiers and a Kampfhund. Kill the dog and then toss a Hand Grenade (or four) down the hallway to clear out any opposition. Move through the halls in the only direction you can until you reach the outside where the car is. Clear a path for Fergus, then wait for him to give you word before jumping in and driving out of the prison. Once you crash, cut the chain with your Laser Cutter and drop into the sewers. Climb back out to street level and enjoy the cut scene.
As soon as you have control, jump into the water and swim after Fergus and Anya. Use the Laser Cutter to remove the chain and then follow Fergus a bit further, ending the chapter.