You pick up the quest from the bulletin board at the seven cats inn. Is that the name of it? I can't remember. It's the board in front of the inn with the cats, anyway. At least I think it is. Unless I'm thinking of Hearts of Stone. It might already be in your quest log. Check yer log first, then try the board.
HoS kicks of at the Seven Cats Inn. And I've checked the quest log a few times and it isn't listed. I also checked every message board I could find, and it wasn't there either. I can't even start it from the main menu.