There are more people at the hideout, now that you've liberated Camp Belica. This time, you are in charge of finding welding equipment for Set Roth.
Before you begin, head into the archive room and look behind the door to find Anne sitting on the floor crying about her lost wedding ring. Once you finish talking to her, go to the third floor and you'll find it just outside of where you can flush the toilet. Strangely enough, we didn't notice it until after we flushed the toilet, so keep that in mind. Still on the third floor, go through the closed door and look at the bench to see that Fergus borrowed the welding equipment.
Head to the first floor and return the ring to Anne who will be sitting in the same spot. This will give you a Gold Vase for your trouble. Next, go back out to the hangers were the helicopters are stored. Once there, you'll find Fergus, who tells you to go back to the first floor of the hideout and to the main room where Anya is always sitting. Return to the hideout and ask Bombate to move out of your way so you can find the welder.
Use your Laserkraftwerk to cut a hole you can crawl through, then drop into the water and pick up the welder. Now swim forward and you can swim up. Resurface to listen in on an optional conversation.
Go back under water and keep going in the direction you were originally. Take a right and climb the ladder to find a charger for the Laserkraftwerk. Jump to the next platform, then look up and cut the chains to drop another ladder that you can climb.
Once you reach the top of the ladder, go right and find the Strobe upgrade. Head in the only direction you can until you reach a large room with a portion of the wall missing, allowing you to pass through to the next area. Before you do, search the side room to the right of the door you just went through.
Drop into the area that shows several hanging charge kits. Cut all the chains, then charge up before you pull the lever in the corner of the room, causing two robots to emerge.
Set your Laserkraftwerk to shoot, then unleash on each of the two robots. If you run out of juice, use the charge kits laying around to top up while you stay in cover. When both robots are down, head through the open door.
Head in the only direction you can, cutting your way through any obstacles and eventually dropping into the archives room. Once you give the welding equipment to Set, take the note he gives you to Anya (all of three feet away and within earshot of Set) to complete the chapter.
Tip: Visiting your bedroom on the second level and then choosing to sleep will trigger a very cool dream that involves Tekla. It won't hinder your progress through the chapter, but it will grant you a health upgrade.