So... it talks about this Arrogance storyline in the changelog, but not the actual specifics to start it? Just 'some uniques in the camp'. That's ridiculously vague. Anymore info? It could take forever trying to get it to happen otherwise.
So the storyline is entirely within the mountains, it starts with In Pursuit of Arogance, which, if you complete it, you get a special assignment, Treachery Most Foul.
After that, you can either free the drow or turn her into a succubus, the drow unique is required to continue the plot.
The drow gives a new option with the Sable Masquerade mission, where you have to send the drow as the dom and you go as the sub. It's very dangerous, with a bad end on crit fail. On a crit success, you get another unique drow, and that's as far as it went until now