Talk to the man behind the desk and he will point your way. Go through the right door. In the big room turn left and enter Private Viewing Rooms. Use the Laser Etched Key on the terminal.
Move to the next room and use the key on another terminal. Examine the chest that appeared. Use the terminal again and enter the password 1021.
You've found a Cryptex, a puzzle that will accompany you almost to the very end of the game. Look at the suitcase closely again. Go to the desk on the left, open a drawer and take one Paper Clip. Use it on the box that's inside the case. You found a clue. The password you should enter into the Cryptex is GRAIL.
After a cut-scene leave the room and go back to the big hall with elevators. Turn left and use Security Card Lvl 1 on a card reader. Enter the elevator and help Sophie up when it's stopped. Use the gauge to open a way outside.
Turn right and enter the door over there. There's a bandage on the floor and a Mars Sphere between the cases. Leave and go to the door that leads to Bank Offices.
There are two guards in this room and it's best to take care of them in the first place. Try to stealth-attack them. Near a desk marked on the map with (*) there's Da Vinci's Ballista (also marked on the screenshot below).
Go to the Administrator's office. Approach the computer and use your Security Card on it. Enter the code 867530. It's no use, you'll have to get a new code. Go to Chatal's Office across the room.
Use the UV Light on the painting. You'll notice fingerprints. Move the painting and you'll see a safe. Open it by entering the pass 728559 (it's written on a note in the desk drawer) and take a File Cabinet Key from there.
Go to the File Room and use the File Cabinet Key to open a drawer marked System Passwords. You got a new password: 260924. Go back to Admin's Office and use your Security Card on the computer once again, this time using the new pass. Now use the updated card on the terminal near the entrance to the offices.
Go all the way downstairs and enter Atrium once again, this time on a lower level. Sneak across the room to reach Deposit and Server Area.
Go forth until you reach a huge room with a lot of small cabins labeled Salle Privee. There are two guards in here, but you don't have to approach them at all. Find the room shown below (look where the terminal is on the screen and find this location) to find an Iron Coin.
Find the Security Card Terminal in one of the corners. There's an Air Vent near it - enter it with Sophie. When you're inside, knock out a guard and sneak into the small room ahead. Once in there, take care of another guard and use your Security Card on Security Card Upgrade Terminal. Leave the room by using the updated card on the door.
Go back to Atrium and sneak past the guards to the Loading Docks.
Use the Security Card on another terminal. There's a corridor with some guards before you. Do what you will with them, it's best to stealth-attack. At the end of the corridor use the Car Keys (you got it from the bank director a while ago) on the Truck Door.