To get the quest "A Brotherhood Betrayed" you must travel to the city of Bruma and find Bradon Lirrian's House. As you walk in you'll notice two guards a woman and a man's corpse. About 5 seconds after you walk in the Guard Captain will tell you that there is a Investiagation going on. You will have to persuade him to tell you who killed him. The killer is Raynil Dralas (Sorry if I misspelled his name) And apperantly he is a vampire killer. Bradon Lirrian was apperantly a vampire too. So you get suggested By the Guard Captain(or the wife cuz i can't remember) to go to Olav's Tap and Tack (Sorry again if i misspelled it). Olav the tavern owner tells you that he stayed in the the last room but you have to persuade him tho get the key. If you get you go in and see a little room and you must look around for a clue.
If you look behind a dresser you will find a book called (I forget the name) Journal.It's really long and there isn't really anything important in it. If you show the book to the Guard Captain he will want to meet with you at the tavern where you got the book an hour later. Then he will tell you that Raynil was spotted near a cavern outside of Bruma. He tells you that he can't send any guards because he might run off so you have to get him. When you get there you will see Raynil standing there then you must talk to him and he talks about a bunch of crap how he won't surrender. So you have to kill him and he has three keys on his body. Bradon's Key, Raynil"s key and that guy's name I can't remember's key.
The keys unlock a chest in the cave which an amulet is in. If you bring the amulet to the wife she says a word and it enchants and you get to keep it.
-Raynil has light armor on and is very easy
-If you tamper with Bradon's Corpse you will be fined a bounty of 500 septims
-Very Short Quest
-Long ago Raynil, Bradon and Gelborne (I remember the name now!) were adventurers and found the amulet and stored it in that chest.