In this level, you have to escape from the Apartment Block getting out the back door of it, eventually reaching the top (fourth) floor. This is a somewhat timed event, because the gendarmes break down the door to the apartment building and throw gas bombs inside. If you do not make it to the top soon enough, you will die from the gas. Additionally, if you run back down the stairs and approach the entrance where the two gendarmes are waiting outside, Lara surrenders and the game is over.

Ground floor - Facing the entrance, there is a movable metal locker on the right. You can pull it in front of the doors (a shown in this screenshot), but this will not prevent the gendarmes from breaking into the Apartment Block. If you do not pull the metal locker, they will enter the building when you step on the second set of the stairs. If you pull it, they will enter when you turn right on the first floor. If you want, you can then go back down again and kill the only gendarme that enters the building, or wait until later and take the advantage of the elevator that can take you up quickly. Since you have no ammo in your possession, you have to kill him hand-to-hand (thanks to SYS for letting us know about this kill).

The door on the left will not open and the elevator is out of order (for now). To proceed, you have to use the stairs.

First floor - Go up the stairs to reach the 1st floor. At this point, the gendarmes break in and throw gas bombs. A breath bar appears beneath your health which will decrease when you breathe gas. This, however, damages Lara so keep an eye on your health bar. Go to the right around the two corners and step on the broken stairs. Jump over the gap and get to the second floor.

(Note - If you are having troubles with the gas bombs that the gendarmes throw, you can avoid triggering their appearance and reach the top floor at your ease. When you go up the first flight of stairs, turn around to face the opening in the stairs above. Take a running jump to grab the edge of the opening and pull up, as shown in this screenshot. Turn around, jump the gap and continue upwards. The gendarmes appear when you reach the 1st floor and since there is nothing interesting there, you can completely avoid it. Thanks to Shrensh about the hint.)

Second floor - As soon as you reach the second floor, some rocks of the derelict apartment fall down, collapsing the floor on the right. There is a locked door in the hallway on the left, but you do not have the key.So, turn right and take a running jump over the gap. Grab the opposite side and pull up. Follow the corridor to a short hallway and pick up the Health Pills (20% of health). Exit the hallway and pull the movable s away from the stairs. Go up to the third floor.

Third floor - Pick up the Small Medipack (60% of health) in the hallway on the left and open the door to get a strength upgrade. Look inside the two green cabinets. Get the V-Packer Cartridges from the left and the K2 Impactor Battery from the right hand cabinet. Exit the room and follow the corridor to the other side. Enter the short hallway and pick up the Health Bandages at the end.

Fourth floor - Go up the stairs that lead to the fourth floor. The fallen rocks prevent you from continuing, so you have to find another way. With the stairs you just went up to your back, grab the movable box at the top and pull it as much as you can. However, you cannot move the box if you have not got the strength upgrade. Climb on the box and turn to face the railing (as shown in this screenshot). Take a standing jump to grab the railing and pull up.

Open the door on the right and enter the room. Pick up the Lift Maintenance Key from the floor and use it to the door on the left if you want to end the level now. If you want all the pick-ups, get the Apartment Key from the hook on the wall that opens the locked door on the second floor.

Going back to the 2nd floor - Use the switch to call the elevator. Exit the room, enter the elevator and press '2' to go to the second floor. Exit the elevator and jump across the gap. Go straight to the hallway and use the Apartment Key to open the door. Get the Vector-R35 Gun from the locker, the Chocolate Bar from the left drawer of the desk and the V-Packer Cartridges from the right hand drawer. If you want, you can go down and kill the gendarme that has entered the building. You have to be quick though, because if he draws his weapon, Lara will surender.

Make your way back to the second floor, enter the elevator and return to the fourth floor. Enter the room where you used the switch for the elevator and open the door opposite the entrance.