There's a group of enemies guarding the door at the other end of the parking garage. You can clear them out easily with a bit a stealth. When you spot the group by the two cars parked in front of the door, click the Left Stick to crouch and then move to the pillar to your left. Sneak along this row of pillars and look for a yellow gas canister by the second-to-last pillar. Pick up the canister, hurl it at the group of enemies and shoot it once it's between the two cars. With any luck, the blast will have killed all of them.
Clearing the parking garage
When the parking garage is clear of enemies, approach the door beyond the two parked cars and open it. Beyond the door, climb up the stairs and sprint to the other end of the walkway you come to. Move through the open doorway next to the elevator at the end of the walkway and head up the stairs to reach the next level.
Once you're on the second level, some enemies will appear on the walkway on the other side of the building. Kane is on this walkway, but he won't be able to deal with these enemies if he's being controlled by AI. These enemies will fire at you too, so it's best to hang back until they've been dealt with. If you have a sniper rifle from the previous level, use it to put them down. Take cover in one of the balconies, but don't move too far up the walkway or another batch of enemies will spawn.
Continue down the walkway after clearing Kane's side and take cover behind the pillar at the second-to-last balcony. Three enemies will appear at the other end of the walkway at this point. Pick them off with your weapon when they pop out from cover, then head through the doorway at the other end of the walkway and take the stairs to the third floor.
Gun your way to the fourth floor.
At the top of the stairs, take cover by the corner and gun down the enemies at the start of the walkway. You can blindfire by simply pressing RT/R1 while behind cover without holding LT/L1. Move up to the closest balcony after killing the first couple of enemies. Two more enemies will appear at the other end of the walkway; dispatch them from afar before pushing forward. Take cover by the corner and eliminate any enemies visible on the other side. Once both walkways are clear, open the door between the two and proceed up the stairs to the fourth floor.
Once up the stairs, turn right and take cover behind the railing. Pick up the gas canister here, throw it at the two enemies covering behind the washing machine and stove in the middle of the walkway and then shoot the can to eliminate them. An enemy may have survived, so take cover behind the stove or washing machine and ensure the area is clear before vaulting over.
Two more enemies will appear at the other end of the walkway and some more on the fifth floor walkway on the other side of the building. Quickly take down the enemies that appear on your side of the walkway, then vault over the stove there and sprint into Xiu's apartment.
Protect Xiu from Shangsi's men.
After the cutscene, take cover behind the chair and shoot at the enemies on the walkway across from the window. When those enemies scatter, enter the kitchen and take cover behind the counter. Two enemies will break through the wall in the kitchen. They're using explosives, so keep your distance to avoid being caught in the blast.
Once you've dealt with those two enemies, move through the opening in the wall. Exit into the hallway and make your way to the kitchen. When you regain control over Lynch after the cutscene, look for a sniper rifle on the ground between the double door. Pick up the rifle before entering the living room and then taking cover on the balcony
You must use the sniper rifle to protect Xiu from Shangsi's men. At first, four will come from the right side of the walkway. Take aim with you rifle and lead your shots to put them down as they run by. Two more enemies will then appear on the left. One of these enemies will stop to fire at you while the one in white goes for Xiu. Pick off the enemy that's shooting at you and then quickly take down the other enemy before he can do anything to Xiu.
Continue protecting Xiu from the enemies that appear on the walkway. When she manages to escape, move through the second doorway on the balcony and then make your way out of the apartment and onto the roof. Sprint forward and be ready for a couple of enemies when you come to a ramp. There's nowhere to take cover here, so fallback down the ramp if necessary and gun them down before continuing on. Once you've dealt with both enemies, continue to the other end of the roof, but don't drop down just yet.
Look for a gas canister by the stacked tires at the end of the roof. Pick up this can, then take cover behind the electrical box across from the tires and wait for some enemies to gather in the middle of the area below. Throw the gas can when the time is right and shoot it to set it off. Remain where you are and pick off any other enemies you can see below before dropping down. One of these enemies will have had a sniper rifle, so press down on the D-pad to locate it and then pick up.
Be careful as you make your way through this area, as there are many different cover spots an enemy could be hiding behind. Take the time to ensure the area is clear before pushing forward. As you move forward, more of Shangsi's men will appear on the walkway at the other end. Hang back with your rifle and dispatch them as they pop out from cover to fire.
When the way is clear, head to the other end of the area to trigger a cutscene and complete the chapter.