Run to the very end until you find yourself on a platform with a container. Behind him there is a remote. Click on it for the first time so that the crane moves the container away. Now you need to replace Birkin in the first part of the platform where the container was, and attack. When the monster gets down on his knees, then you return to the console and press it so that the crane turns the container and pushes the monster. The first time the enemy does not fall down, so you will need to repeat the procedure in the second. In the end, Birkin will fall.
Go left along the formed path, open the door and lower the lever to meet with Ada. After the cut-scene, you should go on the funicular to the laboratory. The funicular is located in a large room where you find a T-shaped device.
Before you go to the lab, you can return to the police station. We found the first button with the number 2 earlier; the second one is hidden in another portable safe. To do this, go on the second floor and open the laundry (near the library) with a diamond (pink) key. Having done this, find a portable safe and hack it. You will receive a key «3». Return to the vault on the first floor, place the key on the panel and open the locker 203 to get the hip bag.
If you find a film in the workshop sewage, then show it in a darkroom. You will see a photo of the cache in the table. Go to the S.T.A.R.S office, look in the room on the left where you found the battery, and interact with the table to get a wooden box. Open it in inventory and get an improvement for Lightning Hawk. Now you can return to the sewer and go to the laboratory with Ada.
Follow the only path from the funicular and enter the NEST lab. Examine the room behind the reception desk, where there is a typewriter and storage. Enter the security room through the door opposite the reception desk in order to find a map of the laboratory on the far table. Follow through the door near the entrance, get to the dining room and destroy opponents. Find the stairs; go upstairs and go down to the kitchen. Get out of here and kill the zombies. Go into the bedroom; take away the improvement of the flamethrower from the lockers on the left. Interact with the hand (from the window on the right) to get an electronic chip. Combine it in inventory with an ID-bracelet. Now you can pass through the door with blue panels (for staff).
Go back down the corridor and go through the door with the blue terminal (from the reception area) at the end of the corridor. Open the bridge using the control panel and go to the center of the main shaft. There is a western and eastern wing. You need to go to the east wing, using the terminal with a blue screen. Access to the west wing requires access by a senior employee.
Enter the east wing, look around the lobby, and open the door next to the reception desk to get to the meeting room. From here, go through the door on the left (on the way, pay attention to the laptop).
Go ahead and enter the greenhouse management room. Use the terminal with the strange characters on the right. Imagine that you face the dial, and press the buttons: 3/1/2/3 and 2/0/6/7. This will allow you to unlock both containers in different rooms. If you are playing the game a second time for scenario B, then you need to click on the buttons as follows — 2/0/4/8 and 5/8/3/1.
Use another terminal to get a sprayer cartridge. Enter the greenhouse, find the door on the left and take a look at the testing laboratory. Use the device for mixing liquids on the left. Use the sprayer cartridge and solve the puzzle (you need to fill the tube to the red level). If you are playing the game for the first time, then click on the buttons in the following order: red, green, blue, red, green, blue, red, green. If you play the game for the second time in scenario B, the sequence will be different: blue, red, green, red, blue, red, blue, green, blue, red, green. You will receive a full spray cartridge.