This is a fun and unique enough little quest. I have it as a little pit stop after the Halls of Durrag-Dol before the Heroes dive head-first into Ogres with the Eyes of Chaos and Against the Ogre Horde.
That being said, what is up with the last paragraph of the intro giving away what happened and what's going on? There's no way I'm gonna read that to the Heroes. Not only is there no way they could know all that, but it gives away what they're gonna find in there. They've already put in the amusing little note basically detailing what the villain's plans are. Is that not subtextual enough?
No thanks, spoiler-intro.