This one's delicate, because it's easy to "quest-break" it. Look out for more information using the word "quest breaker", maybe.

You need to do a rather strict order of talking to persons and doing things in this particular quest, I fear.

When you find a big kettle of crazy, it's best not to stir it.
--Dilbert cartoon

"Interplay.some zombiefied unlife thing going on there" - skavenhorde at RPGWatch