Skyrim:The Gray Cowl of Nocturnal

Quick Walkthrough
#Kill the thief in Riften graveyard and read his note.
#Speak to a Riften beggar and break into the strongbox in Bolli's House.
#Obtain the deed from Erikur's House and find the barrel behind The Winking Skeever.
#Locate the key in Silverdrift Lair and retrieve the Ancestral Sword of Clan Ice-Blade.
#Bring the deed and the sword back to the Riften graveyard for your reward.

Detailed Walkthrough
The Gray Cowl
Once you install The Gray Cowl Returns! Creation, this quest will automatically begin. You have heard rumors that the Gray Fox, the legendary leader of the Thieves Guild, is buried in Riften. You decide to investigate to see if he was buried with the Gray Cowl, a Daedric artifact stolen from Nocturnal herself. Make your way to the Riften graveyard and defend yourself from a confused thief who will attack you on sight. Kill him and read the note on his body to learn that he was an acquaintance of the previous Gray Fox, who had died and therefore passed on his Cowl. It seems this thief had the same idea as you and sought to check the grave. The note also mentions a code phrase to use on the town beggars: "Shadow hide you."

Track down either Edda or Snilf and say the phrase to be passed a note from a Stranger. This individual is offering you a job, provided you can break into the strongbox upstairs in Bolli's House for further instructions. You can try to Persuade or Intimidate his wife Nivenor into giving you the key by telling her a thief planted something inside, or you can just pick the lock yourself. Within, you will find a forged deed, ''Nivenor's Journal, and Stranger's Instructions''. You will need to read the instructions to begin the next stage of the job.

The Solitude Job
You are instructed to take the forged deed to Solitude and break into Erikur's House, where you will steal the real land title and deed and replace it with the fake one. However, with a little snooping around the house, you will be pointed towards a Letter to Gisli, which reveals that Gisli and her associates used a young boy as a political puppet in Jehanna to approve land transfers as the most senior member of the Ice-Blade clan, before shipping him off to Riften. If you confront Gisli with this information, you can offer to buy the deed off her for 8,000 gold, or you can attempt to Persuade her with high Speech skill, without ever needing the forged document. You can also simply pickpocket her. 
thumb|right|A stranger in the flesh
Once you have the original deed in hand, head to a barrel behind The Winking Skeever for your next set of instructions. ''Stranger's Final Instructions'' promises to introduce you to the Gray Fox if you enter Silverdrift Lair and recover the Ancestral Sword of Clan Ice-Blade. The sword can be found in a locked chest deep inside the dungeon. Though you can just pick open the lock, you can find the key on the body of a dead draugr. This corpse is distinguished by a lit lantern placed behind it, as well as two "Loot" shadowmarks above it. The chest also contains a document describing the sword, as well as boss-level loot.

Meeting with a Stranger
After you have exited the dungeon with the Ancestral Sword, you will need to return to the Riften graveyard and locate the Gray Fox's tombstone. There, you will find the ''Stranger's Journal'', revealing that the current Gray Fox is in fact the true heir of the Ice-Blade clan. After Gisli's associates poisoned his sister and endangered her orphan son, he knew he had to pass on the Cowl to someone else and return to his old life. The journal ends there, but after reading it you will be immediately confronted by none other than the Gray Fox himself. He will take the sword and the deed from your possession, granting you the Gray Cowl of Nocturnal in return. Having passed on the mantle, the Stranger's true identity is revealed to be Pjofr Ice-Blade, accompanied by his now-rescued nephew Smaref Ice-Blade. On the promise that you not breathe a word of these events to anyone, Pjofr and his charge depart for Jehanna, leaving you with a powerful enchanted light helmet.

Just be sure not to equip the Cowl in the middle of town, as it will turn all guards hostile if they see you wearing it.
 
Quest Stages