This quest begins immediately after Choking the Gallows. With Reeve Selwyn dead, it’s time to speak with Goodwin about the potential identity of the Quill.
Speak with Goodwin at The Nun’s Minster
You’ll find Goodwin at The Nun’s Minster in the northeast of the city of Wincestre. Enter the minster to trigger a cutscene, during which you’ll speak with both Goodwin and King Aelfred. You’ll have a few dialogue options here, but you can choose whatever you want. After the scene a child will approach, asking if you found a charm that belonged to her mother, which Reeve Selwyn may have taken. You won’t have any such charm, but you can offer the child 115 silver instead. Or don’t. The choice is yours.
Follow and Question the Children
After the scene with the child, follow her through the streets of Wincestre. Within a few moments you’ll find a guard trying to take an apple from a child. Assassinate the guard and then speak with the child to ask for any information about the Quill. They will tell you the names of two children who might know more, who can be found nearby. You can use Odin’s Sight to highlight their location in the vicinity, then approach them to begin a cutscene. After the scene, you’ll find the children by the mill to the southeast. Speak with them to begin another scene, during which you’ll need to deal with some thugs.
When the thugs approach the children, you’ll have three options to deal with them. You can either fight them immediately without any further questions, pay them 230 silver to leave, or convince them to go if you have at least 4 Charisma. If you do choose to fight them, try not to harm any innocents nearby. The fight should be an easy one. Whatever you do, once you’ve dealt with them speak with the children again. This time you can ask them some questions. Whatever dialogue option you choose, at the end of it you’ll be given a key to the sewers, and you’ll learn the true name of the Quill: Hilda.
Infiltrate the Quill’s Sewer Hideout
You’ll find the hideout within the sewers of Wincestre, which can be found a short way to the south of where you spoke with the children. Use your raven to locate the entrance more precisely, then open the door with the key given to you by the child. At the bottom of the steps you’ll need to move a barricade, behind which you’ll find some children. You can speak to them to learn of their problems, but they won’t reveal any crucial information. Turn south and slide under the hole in the wall. You’ll then need to kill a number of guards to proceed.
The path to the Quill is fairly linear from here. Just continue through the sewers and kill any guards that you come across. You’ll benefit from having the Advanced Assassination skill here, which will allow you to kill most enemies in one hit with good timing. You will eventually reach an empty room which will trigger a cutscene once you enter it. The scene reveals that the child Aelwyn has been working for Hilda all along. After the scene, don’t bother with the guards and instead immediately climb the wall to the west, where Hilda is firing a crossbow from. Take her out as quickly as possible (she is weak with barely any armor) and then finish off the guards. Confirm the kill on Hilda to begin a cutscene, after which the quest will complete.