Once zoned in, it is the southern-most house near the water, at ( -187, -58, -153 ) /waypoint -187, -58, -153
Kill the mad scientist in the back room at the bottom. This instance does not scale to level, all mobs in zone are level 70 and do not aggro when you kill the mad scientist if you are 81+ (making this one of the fastest loyalty quests to do at level 90). This specific loyalty quest generally takes longer than the others because all of the mobs in the mad scientist's room are agro, and should be killed before encountering the mad scientist himself. Once killed he drops a treasure chest with a key in it.
This instance does scale if you're doing as betrayal quest. (Max level seems to be 70)
Right click the diplomat to free him and head out of the zone through the door in the main room on the bottom floor.