Trinity Restored

You are to meet Karliah at the meeting stone which is located Southeast of riften. There is a small path that leads up to a dark colored stone and Karliah will be waiting here.Talk to her and she will lead you into Nightingale Hall.

Once at the bottom inside the hall, Karliah will direct you to a room to activate the armor stone. Activate the stone and you are given a set of Nightingale Armor and you are then asked to equip the armor and follow Karliah down the hall to a gateto be initiated into the Nightingales. She will then ask if you are ready to take the oath and open the gate when u answer. You stand on the western circle where she begins a ritual and your become initiated.

Karliah then explains that Mercer has stolen the Skeleton Key from the Twilight Sepulcher.