Walk up the stairs labeled "Workplace Solutions." Go through the room and back down the second set of stairs. At the bottom you'll find a locked door and a dead man holding higher quality materials. Break off the lock on the door and enter back into the main room.
From there head in the opposite direction and climb up the stairs. Head through the only open door to enter a large open room. A lady is making noise on the opposite side of the room, and she will attack when you enter.
Leave the room and wait a bit before coming back. The lady and everyone else should be gone. Walk over to the door on the other end to find a busted Access Tuner.
ID Tag and Archive Logs: There is an ID Tag and a recording at the desk in the center of the room.
After you pick up the Access Tuner, the people that were here before will return. There are three of them, and they all walk out of the back door on the right of the second floor. This is also where you want to go. Nearby is a Rewire System Control that you can use to activate the speaker system, distracting your enemies.
Sneak up the stairs on your right and pass through the dining area. Creep into the small room and take a look out the into the next room. Make a run for the door, or sneak past the single enemy. There is a save station in the stairwell.
"Climb down the stairs to enter the next area. Pick up the Revolver and the Keycard from the desk, then open the door in the small hallway behind you.
Schematics: Go down a hall labeled "System Monitoring" to discover a body from a recent Alien attack. Grab the schematics off the wall.
Enter the next room to find the broken flight recorder. At that moment, you'll hear the bangs of the Alien above you. The Data Cell you are looking for is behind a couple of moveable walls.
Simply hit the buttons to have them move. Grab the Data Cell to fix your Access Tuner and open up the door.
ID Tag and Archive Logs: There is a meeting room that can be unlocked with the Access Tuner. Open it up to find the ID Tag inside along with a recording.
Return back to the area where you got the Revolver, then head down the hall to open up another door with the Access Tuner.
One of the computers in this room will disable the alarm system.
Archive Logs: There is a computer with two recordings here.
But it won't disable that Alien. Cower in fear as it enters the room and leaves on the left.
"Calmly make your way back to the stairwell.
Go up a flight of stairs and you'll see a door you can hack through. Now back in the room where you found the Access Tuner, watch or listen as the Alien takes out the foes you were faced with earlier. Now it's time to make your escape.
The Alien will wander around the room, so you will always want to know where the Alien is. Your goal is to get back to the door the girl was trying to open earlier. Go back to the dining area and down the stairs to make it. As soon as you finish hacking the door, run inside and slam the elevator shut.
Remember, if the Alien even catches a glimpse of you trying to pass by, you're going to have to be very lucky to try and ward it off with the current weapons you have.