I recently started a new game as a mage type character. As far as I can tell I haven't done anything wrong yet, haven't stolen anything, etc. In fact, the only quests I've done so far were the initial main quest up to the point where I was appointed thane of Whiterun. Yet as I was walking through the wilderness to Ivarstead, I ran into an assassin who had this Dark Brotherhood assassin's note on him:
As instructed, you are to eliminate [playername] by any means necessary. The Black Sacrament has been performed - somebody wants this poor fool dead. We've already received payment for the contract. Failure is not an option. - Astrid
Who hired the assassin and why?