Objective: Rescue the Remnant prisoners
Exit the building and find the gap in the fence to the west of the Base Camp. Drop down successive ledges to reach the river below. From the first set of icy platforms, you are going to want to swim to another set in the distance to the southeast.
When you arrive, ignore the cave on the northern side of the river for the moment (remember it as we’ll be back later when we have explosives) and instead climb up the largest of the rock structures using the climbing wall. Form here, leap to the climbing wall on the southern side of the river and use your pick axes to reach the top. Loot the barrel here for some resources.
Use the Rope Arrow on the beam sticking out above the platform to the south and then zip line across. Use the climbing walls here to reach the platform at the top. On the ledge here, climb up to the branch of the lone tree and from here leap to the white scrabble wall nearby to climb up to the next area.
There is a pair of enemies in this area. Wait until they are separated and sneak up and take them down (or headshot them with the bow) or wait until they come together and hit them with a Poison Arrow to knock them out simultaneously.
Before entering the ventilation shaft entrance that they were guarding, look to the left for an Explorer’s Satchel. To the right of the entrance, by the pile of wooden debris you’ll find a Survival Cache [10/21]. Enter the vent to continue.
Once inside the building, loot the bin to the left for some reagents. Ignore the stairs on the left for now and open the door here. We’ll be in familiar territory – hop through the broken window ahead to where we encountered the prisoner earlier and use your Lockpick to open the locked door. Inside you’ll find a bin filled with reagents, a crate of Salvage and a chest containing Relic [09/18 – Gulag ID ].
Return to the vent we came in from and this time, let’s head down the stairs. At the bottom you’ll find an open doorway and a guard just inside with his back turned to you. Sneak through the doorway and perform a stealth kill on him. If you flick on your Survival Instincts, you’ll also see a pair of sleeping enemies here. Kill them both.
Head over to the cell door here and unlock it. Move up and free both of the prisoners within. Now backtrack all the way to the ‘Logging Camp’ Base Camp to hand in the side-mission.
Leave the immediate area (use the Base Camp to fast travel to another and then back again) to reset the ally. Once you get back, return inside to speak with the Remnant General once again. He’ll offer you a new side-mission ‘Misguided Intelligence’ .