The first part of this mission has us following our friend for a little while whilst he monologues about story-related stuff. After opening the first door, check out the desk on the right for a lockbox containing ammo . Keep going until you reach the ventilation fans. Work your way through these when the blades stop and continue on after your friend when you reach the end.
When you arrive at a small room where you need to drop down through a hole in the railing on the left to progress, instead continue into the far room and loot the corpse in the corner for +20 Military Grade Rounds . On the ground to the right of the corpse is Diary Note [Note 1/1] . Go back through the door and drop down into the waterway. Climb up and follow your mate through the door on the other side of the room.
As you enter, look at the base of the brick pillar in front of you to see a lockbox. Loot this for some ammo and +20 Military Grade Rounds . Go through the hole at the back of the next room and drop down to the walkway on the right. Climb the ramp to the bottom and use the pipes here to reach a platform around the corner to the right. Get ready for an attack!
As you work your way through this room here a total of 8 nosalises will attack and will enter the area from both the far door and an entrance to the right. Fortunately your friend is here to help. As you clear them out and move through the room, look out for an opening on the right. In here, there is a door you can interact with. Inside are a corpse we can loot for + 30 Military Grade Rounds . Return and follow you friend to the far side of the room.
Continue through the tunnels until you reach the cobweb filled room. Use your lighter to get rid of them. Open the door here to find a corpse with some Grenades . When ready, return to the main room and interact with the metal grating. Work your way through the short tunnel here and drop into the water.
When the torch/night vision goggles are disabled, pull out your lighter and follow your friend through the tunnel. Around halfway through a phone will start ringing. You can interact with it if you like for a Morality Point , although if you ignore it, you will earn an achievement/trophy ‘Nobody’s Home’.
Note: If you ignore the phone during the anomaly, you will unlock the Achievement/trophy ‘Nobody’s Home’.
Continue to follow your friend through the tunnel until you reach a large pool with a waterfall. Walk out, through the waterfall and out the far side for a Morality Point . Continue forward until a scene plays.
After the scene, approach the ladder on the floor and you will be teleported somewhere else. Follow your friend until you reach a dead end. After another short conversation you will be somewhere else once again. Run through the train until you exit the far end and a scene will play.
When you regain control, climb out of the water and follow your buddy into the tunnel. After passing by the hanging cans, look on the desk in front for a Custom Weapon and examine the lockers next to it for ammo, Medkits and +20 Military Grade Rounds . Continue down the near stairs and enter the vehicle nearby.
This will end the mission.