The game recommends you alter your loadout for flashbangs and other non-lethals.
You’ll start wandering around town, but quickly you’ll put on your killer gear. Follow the marker until you reach a doorway. The game will start giving you some tips after that on how to assassinate properly. You don’t get a choice for this bit.
Continue following directions to complete the mission with maximum stealth. Enter the safe house, head to your right, use the light switch to darken the hallway. Move up to the next level. If you hit the light switch here, you’ll attract two guards and you can take them out now. Or you can just sneak as Briggs will tell you, and avoid the combat altogether. Go in the room on the right, exit the window, follow the balcony (take out the guard if you like), climb the wall, look for the window, and expect a guy right inside.
Two more guys are waiting in the next room. It’s easy to mark them and headshot them both. When you come to a locked door, don’t break it in, proceed around the corner. There are FOUR guys in this room, and you can see three of them from the door. Use an execute and it’ll flush out the last guy for an easy kill.
Now things get hairy. Look to sneak up behind guards for easy stealth kills as you make your way across the rooftops, following the marker. When the game suggests looking for alternative routes, it is a cue for you to get sneaky and go around, or be prepared to fight about six militia guys in short order. Do some wall crawling to reach the marker, and you’ll be advised of a High Value Target in the area. Open the window and use the stun gun to drop him easily.
After that you can stock up on ammo, and then you face a long hall. The game recommends you whisper to draw in the nearest attacker. Turning off the light switch and shooting them in the dark is quieter. A guy will hide in a room halfway down on the right if you don’t get him right away. There are three guys in the hall, but three more will come to investigate if you draw attention. Otherwise, you’ll meet them after you exit the hall at the end on the left. Climb up on the stair railing to do a drop attack, they’re really awesome.
There are two guys waiting for you in a garage at the bottom of the stairs, and after that you need to climb a gate, evade or kill a guard dog, and then you’ll get another update from Grim.
When the game tells you to use noisemakers, ignore it. Instead of going through the open gate, look for the closed one. Climb it and look for militia before you go over. When the coast is clear, or when you’ve cleared it, head straight ahead for a low point in the fence across the street.
In this yard, wait for militia or avoid them. NOW use noisemakers to get the dog out of the way, proceed around the outside of the yard, then up the wall to chase the marker, which will put you in the police station at last.
On the ground floor there are four guys. Use the Snake Cam to find them and get the drop on them without being exposed. Take out the lights when you see them, it’ll help. Upstairs, you’ll be told to look for laptops, and the first door you come to holds the guy you’re after.
Now you have to escort your new friend out. If the guards are alerted, they’ll bring reinforcements. Look for the first guy standing at a desk. Mark him and drop him. Go past where he was to a hall. At the end is a light. Shoot it out and a guard will come to look at it. Take him down, and then there’s only one left. Mark him and drop him. Then move to the marker.