Chapter eleven will open with a cut scene, but when it ends you're going to want to take cover and pop into listen mode. At least two Fireflies are going to come after you, and when they are down, two more after that. In fact, there are several waves to deal with, totaling about a dozen adversaries who are all heavily armed and wearing armor.
Tip: Depending on how far you've upgraded listen mode, you may or may not be able to see the far away enemies. Also keep in mind, crouched and stationary foes often don't show up.
These guys move around a lot, so telling you where to go to kill each one would be impossible. Instead, try to stay in the exterior rooms, using the half walls with windows as cover. When one of the Fireflies comes close, pop up and take his head off -- literally -- with a Shotgun round.
As you're working your way through this first area, make sure to loot bodies so that you can obtain the Assault Rifle and any ammunition that dead Fireflies have on them. It isn't terribly effective against body armor, but it does well enough to be a good option. It's also the most common ammunition found from here on out so you might as well use it.
When the area is clear, make sure to visit each room and loot each body, then head toward a curved hallway that has West Wing written above it. Once you head down it, three guards will sprint toward you. Hide behind the counter and let them pass, then turn around and kill them. You could bypass them, but you have another guard ahead who will almost certainly see you, and the last thing you need is these guys sneaking up from behind.
When those three are down, head through the narrow tunnel just past where you encountered them. When you pass into the next area, a lone guard will burst through some double doors. Take him out in whatever way you want since nobody is around to hear him scream. Loot the area, then pass through the doors he came out of and head upstairs.
When you get to the top of the stairs there will be an office just in front of you. Head to it, then use a Shiv to open the door. This place is a gold mine, and if you've hit every Shiv door in the game, you'll unlock the Master of Unlocking trophy. If you haven't, no worries, you can return to our landing page using the links at the top and bottom of this article to find the walkthrough.
Exit the room and take a left, then another one to go through some double doors. Pass through a medical tent, then turn right and go through a door that says Surgery above it. You need to go down the hallway to your left, but it's filled with Fireflies; eight to be exact. The only bonus here is that they have to attack from one direction so long as you stay at the hall's entrance.
Your best bet is to use any leftover Bombs and Molotovs to thin these guys out. Heck, use your Smoke Bombs as well. Once this is over you're pretty much done, and there is no point in having extra weapons sitting in your backpack. Throw everything you have, then take the rest out with the Assault Rifle and move through the doors at the end of the hallway.
When you enter the next area you'll see a single door with a Firefly symbol on the wall to the left of it. Just sprint forward, go through that door, then another to enter the operating room. When you have control of Joel, shoot the doctors and nurses in the head, then pick Ellie up off the table.
Exit the operating room, then turn to your left and make your way through a series of open doors. When you find yourself in a hallway with some windows on the left, run to the end and take a right. As soon as you round the corner, take another right and duck into a locker room. Run to the opposite end, then take a left and go out the door. Run down the hallway straight in front of you and into the elevator to trigger the chapter ending cut scene. When you're ready, let's move on to Chapter 12: Jackson.