Darkness Returns (quest)

Walkthrough
After the Dragonborn kills Mercer Frey, taking the Skeleton Key from his body, Karliah will be adamant that the key has to be returned to Nocturnal's Temple the Twilight Sepulcher.

Enter the Twilight Sepulcher
After you get to the Twilight Sepulcher, again a follower may not enter the place, you will encounter a Nightingale Sentinel, the ghost of Gallus. He will tell you that his power is fading since the Skeleton Key was removed, and warns of the Pilgrim's Path that the Dragonborn must overcome. Obviously, as a former Nightingale he is relieved to see the key return, and hints at additional information available right in this cave.

Retrieve Nystrom's Journal (Optional)
On the east side of the cave the remains of Nystrom together with Nystrom's Journal yield some cryptic (mostly useless, actually) hints on how to navigate the Pilgrim's Path. A random War axe can be found next to the body.

Follow the Pilgrim's Path
Follow the Pilgrim's Path:
 * 1) Kill the Nightingale Sentinel (×5) ghosts.
 * 2) Take the dark path, avoiding the scorching light that massively decreases health and eventually kills.
 * 3) To the left and right of the Statue of Nocturnal there are two lit stone heads, pull the two chains next to them to open the gate behind the statue.
 * 4) Jump into the deep cylindrical pit, to find Anders, and read his last message. Luckily the Skeletal Key will automatically unlock the pit's floor.

Return the Skeleton Key to the Ebonmere
In the middle of the circular room with three niches, place the Skeleton Key into the Ebonmere Lock to have both Nocturnal and Karliah appear.

Listen to Nocturnal
A cut scene with Nocturnal plays out.

Speak to Karliah
Simply speak to Karliah.

Choose Nightingale Role
With the key returned the Dragonborn can now take on the role as Agent of Nocturnal, but for now has to choose one of the three options:


 * Agent of Stealth
 * Agent of Subterfuge
 * Agent of Strife

It is possible to return to the Inner Sanctum at some later time and choose another role.

Thus ends the main quest line of the Thieves' Guild.

Die Rückkehr der Finsternis (Aufgabe)