The Investigate the Subway in the Evacuation Zone mission will take you deep down under the surface subway in Control Resonant. It will be necessary for you to move along the tracks, go past derelict train carriages, battle with several Molds, and go down even deeper tunnels. On your way there, you will come across a weird altar from which you can interact with the TV.
How to Reach the Subway Fault
The Subway Fault leads you to the subway tunnel beneath the Railyard Substation in Evacuation Zone 5. Prior to proceeding to the tunnel, ensure that you have the Level 1 Keycard in hand because it will be required to unlock the Level 1 FBC doors on your path.
Begin at the ground floor in Evacuation Zone 5 and pass through the building to the subway tunnel stairs outside. Once you approach the tunnel entrance, you will hear an echo of Jesse. This will confirm that you are at the right entrance. Proceed into the tunnel and head further downstairs through the mezzanine and tiled stairs until you reach the platform next to a broken-down train.
Follow the Subway Tracks
Start by descending to the level of the rails, and follow the tracks into the round tunnel. Continue walking until you reach the immobile train that is standing in your path. You will be able to go inside the train and get past it. Once you have passed the train, continue walking along the tracks into the subway system.
Climb to the Upper Level
Finally, you will end up facing a shaft which is covered in turquoise crystal formations. Climb up using the ladder situated in the center of the area. Follow the tracks which have grown over with vegetation until you reach a maintenance door. Use the door and climb down to the lower tracks.
On your way to the door, a Resonant creature will attack you; eliminate it and move forward. Once you have killed the Resonant creature, jump the wall and land on the graffiti-filled platform. Find the broken part of the wall and jump through it. You will end up in a small corridor containing sleeping mats. Continue moving forward, and you will be back on the tracks near train MT386.
Reach the Lower Tunnels
Go further ahead and hop over the pipes and any other obstacles along the way. Follow the corridors of the service until you find a sloping terrain with teal coloration. Go down the slope to access the lower levels of the subway.
You will soon enter an area where there is a big tunnel with lots of mold. Enemies waiting for you in this area include Mold Hosts, Bloomed Spore Mothers, and Mold Blights. After defeating these enemies, go ahead through the big arched tunnel until you reach a huge shaft with subway trains hanging from the center of the pit.
Descend Through the Train Cars
Drop into the shaft and use the hanging train cars to move through the shaft. Instead of falling to the very bottom of the shaft, make sure to land on top of the hanging trains. This is done to ensure that you do not take too much fall damage. At the bottom of the shaft, you will notice a teal mold floor. Defeat all the Mold enemies, whether they fly or crawl, and move ahead into the glowing railway tunnel.
Move forward until you see the concrete bridge. Cross the bridge and head to the altar where there is a television. Activate the television and have a conversation with the Board. You will be asked to move to another objective called “Enter the Fault.”
