This is the first part of a chain of quests leading to the final showdown of the defias leader, Edwin van Cleef. So if you?re planning to visit the Deadmines, make sure to do these quests first. You begin this one by speaking to Gryan Stoutmantle in Sentinel Hill. He says:

The band of wretches responsible for driving the good people of Westfall from the land call themselves The Defias Brotherhood.  I need you to infiltrate this clan of thugs.  We need to know who heads up the cartel and where they are hiding out.  In Lakeshire, in the inn, there is a rogue by the name of Wiley who owes me a favor.

Travel to Lakeshire in the Redridge Mountains, east of Elwynn, and find out what you can.

Travel to Lakeshire
Speak to Wiley

Now jump on a gryphon to Redridge, or run east through Elwynn Forest if you haven?t been there before. You will find Wiley the Black on the second floor of the local inn. Speak to him and he will give you the next part of this quest line, The Defias Brotherhood II.