Once you've completed Quest 7 (Mad Mages), Logain will begin talking to you about the Knights
Going mad. They are across from where you went for Mad Mages. You must go through and obtain a Note.
It's thru the door with 3 Knights to the right. But you must go to the left to the room with about
7 Knights to obtain the key. It's as simple as that. This map
You then return to Logain and he will give you gold, experience, and the key to Quest 11 (Zombie 1 aka Loisan's house).
I wouldn't suggest you doing
quest 11 yet, I would go to Theif Master or Mama Bear first.
Please refer to the links for instructions.