Skyrim:The Lost Expedition

Quick Walkthrough
#Speak to Calcelmo and ask to investigate the dig site.
#Recover Alethius' note.
#Find the expedition members and recover their journals.
#Re-activate Nchuand-Zel's automated defenses.
#Speak to Calcelmo about the expedition.

Detailed Walkthrough
Proceed inside Nchuand-Zel until you encounter Nimhe. After killing Nimhe, head up the steps to find the dead body of Alethius. Pick up the notes next to his body to begin this quest.

Cut through the webbing behind his body to enter Nchuand-Zel. In the first hallway there is a pressure pad that activates a spear trap. Continuing on, you will emerge into a huge open cavern with multiple levels, with Falmer standing guard on a few of the connecting walkways. At the end of the large walkway is the entrance to Nchuand-Zel Quarters.

In this zone, you will encounter quite a number of Falmer, usually in groups. After exiting the first corridor, there will be two ways to go: downstairs or straight ahead. Proceed straight ahead first. When you reach a second set of stairs, there is an adept-locked door to the right containing random leveled loot. At the bottom of these stairs is a large group of Falmer (around 4 - 5). Proceed through these corridors until you come across a large door. To the left of this door is a small room with a bunch of Dwemer items. The door leads to a small balcony overlooking Nchuand-Zel, and also contains a chest with random leveled loot. Head back inside Nchuand-Zel Quarters.

Head back to the first set of descending stairs you encountered after coming into the Quarters and proceed down them. You will encounter more Falmer along the way. Head up some stairs, making sure to avoid the rune trap at the top, and you will notice a table to the right against a wall. On this table is ''Stromm's Diary'', which you will need for the quest. After picking this up, you will be tasked to collect three other journals: Erj's, Krag's and Staubin's. In the area to the left of this table are the actual Living Quarters, where you will find many Dwemer items, as well as beds you can sleep in. Head back out and past the table until you get to what looks to be a torture room. On the left-hand side of the doorway (as you enter the room) is a lever. Pulling it activates the spike trap on the table next to you. Now head back out to the door where you entered the Quarters from.

Backtrack a short distance until you have to turn right (which faces you towards the entrance of the zone). Instead of turning right, head to the left where a ramp will lead you to a lower level. You will notice the balcony you arrived at earlier when heading down this ramp. At the bottom, there are two ways to go. Heading left leads you to a platform a Falmer is (or was) standing on. Instead, go straight down the next ramp which will lead you to the bottom of the area. An adept level gate on your right holds a chest with random loot. Head down the path away from the gate. The path leads to a body of water, so head in and start swimming around to the left until you see another ramp (underwater) leading to a door, which leads to Nchuand-Zel Armory. Enter it. (Note: It is possible to get here by jumping off any of the bridges you have been traversing, or by jumping off the balcony from earlier).

Upon entering the Armory, there are two ways to go: down the corridor or up the stairs. Head through the corridor first. Soon you will come across an adept locked gate, and upon unlocking you will have to go up some stairs. At the top of the stairs is a dead Falmer and Erj's body, along with his diary and a chest containing random loot. The first room to the left at the top of the stairs has nothing of interest, but the second room to the left has an expert-locked gate which leads to a chest with some random loot. Across from that gate is another expert-locked gate with a full set of Dwarven armor. Upon approaching the next gate, a Falmer appears and a Dwarven Sphere awakens and does battle with it. The next gate has nothing of interest and after that is another corridor. The pressure plate ahead of you will activate a spear trap behind you. The next pressure plate up the stairs activates a flame spout trap behind you. After this, there will be two ways to go. Head right. A Falmer is keeping watch ahead of you. Just ahead of him are the stairs you saw when first entering this area (heading through the corridor instead of the steps guarantees you will avoid the traps should you stand on a pressure plate). Head back and go the other way, which brings you to a door leading to Nchuand-Zel.

Upon going through the door, you will immediately come across Krag's body and his journal. Head up the ramp (past an Imperial soldier's corpse) which brings you to the final zone: Nchuand-Zel Control. The rocky ramp to the right of the door serves as a shortcut back to the entrance of the ruin.

After entering the door, continue through the corridor, encountering more Falmer along the way. A pressure plate just before the upwards ramp activates an dart trap, so either avoid it or wait until it finishes. At the end of the corridor at the top of the ramp are two more Falmer; you will want to attack the one on the right first as it magic-based in combat. The other has both a bow and a sword. The pressure plate in the middle of this corridor activates a spike trap from the ceiling. Be careful of this if you have a follower, as he or she is likely to trigger this trap; even if your follower is essential/permanent, the spikes can kill him or her if they are still going while he/she is crouched. At the end of the corridor, turn left and you will see Staubin's body and his journal, along with a damaged Dwarven Spider. Picking up the final journal grants you a new objective: Re-activate Nchuand-Zel's defenses. 

Head past the body and up the steps where you will encounter some Dwarven constructs. At first, there should only be a few Dwarven Spider Workers, but fighting them awakens a couple of Dwarven Spheres. Fighting these can draw the attention of a Falmer, if it was not defeated before the Spheres turned their focus towards you.  Continue to the end and you will reach a room with a table and a chest. On top of the table is a leveled healing potion, a Falmer Bow, and a lever. Pulling the lever completes the objective and opens up the gate behind you, so head through. Through the gate and at the end of the corridor is a chest. Now just jump off the bridge to end up back at the entrance door.

Upon exiting, you will see a Dwarven automaton fighting a Falmer. This is actually happening all throughout the ruin. Feel free to stay and join the fight, or just head up the ramp to the left and back to the entrance of Nchuand-Zel. Head back to Understone Keep and talk to Calcelmo to receive your reward and finish the quest. Your arrow may point back to the Armory at this point; see "Bugs".

Reward
 

Bugs
 
 
 
A workaround is to jump into the water and the follower will follow. It is then possible to climb the spiral ramp back to the exit level.
Alternatively, before jumping down onto the exit path yourself, order your follower to wait at the end of the ledge. You can then use the weakest form of the Unrelenting Force shout to push your follower over the edge and onto the main path. Be careful not to use Unrelenting Force's full power or you are likely to send your follower flying into the water.
You could also part ways with your follower before jumping off the ledge. They should be back home upon exiting.
 
Move the body further from the webbing and try again.
Use concentration spells like Flames on the webbing.
 
 
 
The game may be treating your swings as hitting Alesius' body. Try dragging him further away from the webbing.

Quest Stages