When you gain control of Max, you'll be through head first into a gun fight. I highly recommend you go into Bullet Time as soon as you come through the door. There will be three men staring you in the face and you may be able to get at least one. After you get that first one, Shoot Dodge forward and right to try and get the other two. This should put you comfortably behind cover. This cover is fantastic because everything in this office is low so you can shoot over it and see better but you're still protected. From here you can basically clear the entire room from safety. Most of the remaining enemies (about five or so) will be on the right side or straight up the middle of the room.
After the coast is clear, pick up weapons because they've got a lot of good stuff if you want it and then inspect the office just by the door you first came through. This is Victor's office and on the desk is a File on Fabiana and Rodrigo's Email in the laptop here. Take that and then go back into the main room. Cross the room and in the first glass office (the biggest of them) will be part of the Golden MD-97L. Two offices down will be some Painkillers. Take it all and then catch up with the kid.
You'll enter the next room and immediately get shot at. Four enemies will come through the door on the far end. If you have some Bullet Time, you might be able to take out a couple and then Shoot Dodge behind the table in front of you. If not, I would Shoot Dodge to the cover that the IT guy is behind. You still should be able to get one or two people (more if you're good). If you managed to take any out during the opening volley, it shouldn't be too hard as long as you watch your flanks. These guys wear good armor and aren't afraid to be aggressive. Your cover is also very narrow allowing them to get around it quickly.
Before you leave, one of the models in the room can be examined as a clue and they can all be destroyed for an achievement. Make sure you examine it first, then clear every model by shooting it including the couple on the long conference table. If the enemies shot one up first then you can't get credit for it however they should only ever do this by accident or if you use one for cover. After you've destroyed all of them, the achievement should unlock.
*Achievement: Amidst the Wreckage
When you move ahead, you'll come to a very large open room with a window along the left side and lots of desks. Max will automatically take cover behind some cabinets. There's also a sort of indented closet along the right wall but there is nowhere inside that you can go for cover so don't go in there or you'll die.
Pop up in Bullet Time and take out the two people directly in front of you and check for a man to your left. Move up the right side now and Shoot Dodge behind the next desk and take out any more enemies you can see. There should only be a few more at this point and mostly up this right side. Once they are dead, a cutscene will happen and a group of enemies will come through the windows. Thankfully, you'll be placed on the other side of the room. They will have some good cover though but if you want to overcome that, the best bet is to slowly work your way around the outside to the right. There's about a dozen in total and they are going to be all over this room. Just make liberal use of Shoot Dodge to move from cover to cover since the cover is of convenient placement and height.
It's not an easy fight but once you've cleaned the room out, move ahead towards the stairs. After a cutscene, you'll be outside. Turn around and you should see part of the MD-97L on the left under the balcony. Continue on the way you were going and follow the wall. Along the wall to the right will be a bathroom with Painkillers inside and further along the wall will be a clue. It will be Three Pictures of the Brancos. At the end of the walkway, go through the large double doors on the right.
After the secretary, you'll have a jeep come flying through the front door at you. The only way to survive is to kill the driver though you should also try and kill the gunmen after if you can. Your first priority is the driver though. Immediately after, Max will jump over the desk and a group of six or so enemies will come through the front door. Be ready for them and see if you can't get a few of them now. They'll spread out by the door but shouldn't be a huge problem.
After you've gotten rid of them, a group of three more men will come through the front door, one of which is heavily armored with a helmet and a large machine gun. You need to put quite a few rounds into his head to dislodge his helmet, then hit him in the head one more time to kill him. Once he's dead, the other two will be a cake walk. Before going back upstairs, check the models along the wall near the reception desk. One of them will have the last part of the MD-97L.
You'll head upstairs to investigate and after a few minutes, you'll be outside in a pool. Climb up out of the pool into the office directly ahead of you. Climb the stairs to the top and go through the shutter at the top. A man will approach you. Take his gun and kill him. As you pass over the IT kid, examine his body for a clue.
As you get past the kid, and round the corner you will be attacked by a man or two. They may come up the middle or up the left side. Kill him/them and go up the middle. The ground will break up but you'll get past it. In the next room will be three guys and a filing cabinet. Kill them (should be an easy Bullet Time/Shoot Dodge) and then push the cabinet over so you can use it as a bridge. Continue along and cross over the wooden beams to get to the other side. Keep walking and you'll finish the chapter.
