Survive Sevastopol with Prima’s Alien: Isolation Walkthrough.
This mission will kick off with your objective updating and asking you to Take the Elevator to the Solomons Galleria. Exit the room and move forward, choosing the option to Use Plasma Torch to cut the panel off the door and open it. Go straight until there is an opening on your left, taking that and then another on your right a short distance ahead. You're on the right track when you descend some stairs and find the Shotgun laying in the lap of a dead body. Pick it up and then the Keycard after it. Make your way through this room and use the keycard to open the door at the far end.
Passing through this door will take you all the way back to the Spaceflight Terminal you passed through in Mission 2: Welcome to Sevastopol, just about the time you met Axel in front of the big door with the number 42 on it. Go through the giant door and move forward a ways, hopping on the elevator with the Solomons Galleria sign above it. Press the button to take a ride.
When the ride is over, your objective will be to Return to the Marshal Bureau. Step off the elevator and head to the left, turning left when you reach a corridor. Follow it until you reach some metal shutters and receive and updated objective to Restore Power to the Galleria Security Shutters.
Standing at the metal gate, look down and to your right at what looks like a high-tech vacuum cleaner, choosing the option to Activate when it pops up. When the thing starts to drive off, go with the only option that makes sense and follow it. When the juiced up dust buster finally stops, hop into the nearby ventilation shaft and move in the only direction you can until you emerge at a table with the EMP V.2 blueprints.
From the table, turn to your right and go up the steps, choosing the option to Use Lever to open the door at the top. Go through and turn left, following the corridor to another ingress (fancy word for door) and one more Use Lever option. Once on the other side, loot the area and then remove the floor cover, moving through the maintenance shaft in the only available direction. When you emerge, search the room for a 2000-KJVS Generator and choose the option to Use. This will restore power and allow you to pass through the room's only door. The game should also update your objective, which remains exactly the same as before, Return to the Marshal Bureau.
The next room is going to be filled with Synthetics having a bad day and slaughtering some humans. Seems like a perfect time to give your Shotgun a workout, so crack it out and start busting caps. Two headshots per Android should do it, so be precise. When all of the Synthetic scum are down, head toward the bright lights and turn left, following the corridor until you're ambushed by a lone gunman. Take him out and search his body for goodies and ammunition.
Head down the ramp where the gunman ambushed you and turn right, going toward a large door and then through to the other side. Turn to your right and grab the map along the wall, then move forward and take your first left. The large metal gate should raise, but be ready to fight a Synthetic as soon as it does. Your best bet here is the Shotgun or Flamethrower, and when the guy falls, turn right and pass under the Colonial Marshals sign and up the stairs.
This path is a no go, and soon after hearing some disturbing events over the radio, your objective will update to Find an Alternate Route. Backtrack down the stairs and all the way back to where you just picked up the map a few moments ago. If you go left, you'll be back at the ramp where the ambush took place, but you need to go straight and up the nearby stairs. You'll know you're in the right place if you have to deal with another ambush.
With your attacker down, head up the second flight of stairs and through the big metal door. The gate you need to go through is immediately to your left, but snag the map from the right side of the corridor first. It can't hurt. When you're through the door, move forward a few feet and through another metal gate to find an opportunity to save your game.
From the save game mechanism, head to your left into a room with a Sevastopol terminal. Look at it if you want, but when you're done, exit through an unmarked door and make your way through to another that requires you to Use Lever.
You should be met with bright lights and a grumpy Synthetic. Take the Android punk down with whatever weapon suits you, then turn right, taking the first door on your left and descending two flights of stairs. When you reach the bottom and enter the corridor, feel free to explore any of the nearby rooms, but when you're done, you'll be looking to enter a vent that's on the far left side of where you emerged from the stairwell.
Following the vent all the way through will bring you out extremely close to your objective. Pass into the next room, then take a right and move forward. You'll eventually meet up with Ricardo in an area full of dead bodies. Make sure to search them, as well as the entire area as the two of you chat.
Your objective will update to Find Samuels in Seegson Synthetics, and shortly after to Take the Transit to the SCIMED Tower. Exit the area through a door that's located to the right of where Ricardo was sitting, then walk down some steps and go through an automatic door on your right. Walk down some more steps and pass through a corridor to find a lone Synthetic patrolling. Mess him up before continuing your journey through a large metal gate on your left, and one more that is also on your left. This should see you standing at a large set of steps with a Synthetic nearby. Take him out like you did the last, ascending the stairs and continuing your trend of moving left. Before long you'll see an opening to your right and the Towerlink Transit System.
Move into the area, pressing forward and down some stairs to Towerlink 03. It will be the one with the sign above it that says Destination SCIMED Tower. Watch out for the Synthetic nearby, but when the coast is clear, call the transit and hop aboard. This will update your objective to Get to Sevastopol SCI/MED Tower and bring an end to the mission.
Continue to Alien: Isolation - Mission 12: Synthetic Solution.