There are two rows of houses in an arc down the bottom of the screen. From memory, it is in about the middle of the bottom row, entered from the north side. It may move around as its a single instance dungeon - so try all the doors, the name comes up when you select the door.
Once you are in DO NOT attack the customers - look for the instigator hiding at the back. He's actually pretty easy.
Happy hunting
(ielond, 16 enchanter, najena)