Fall in the inhospitable domains in the Ravenloft campaign world, Bluetspur is the cruelest and most gruesome.
Nothing grows in the endless night, and lightning periodically falls like rain.
The only place to escape those storms is inside the mind flayers' complex under Mt. Makab, but that is the last place where any sane person would want to go.
The High Master Mithid has been hatching black plots by hatching vampiric mind flayers in his laboratories!
His prodigies are horribly insane, but if he can complete his plans, he will achieve a new level of dark immortality.
A pair of heroes has stolen the key to his success, but they have paid a heavy price for their bravery and are in desperate need of aid unlooked for.
Meanwhile, the Lord of the Realm watches over the proceedings and plays havoc with the wits of both sides, sapping strength and will with all-powerful thoughts of darkness.
A party of adventures will need all of their skills to escape this black domain without the loss of life, power, or sanity!
Ugh. What a piece of shit. Once again, early designers of adventures prove they had NO idea what to do with high level characters. The characters aren't made to feel horror through storytelling; no, instead it is through complete powerlessness and railroading into a series of encounters that the players have almost literally no choice in -- go this way or die. Do this or die. Doesn't matter how powerful you are -- nothing you do works or has any effect. Even the final battle is much more narrative by NPC actions than the PCs. The monsters are repetitive (I cannot emphasize enough how often you fight: 10 mind flayers, 20 drow fighters, 20 duergar. Literally the same encounter over and over) and the encounters are often dreams that have no chance of being won. This is the least player agency I've ever seen in an adventure and the writer and editors should frankly be ashamed.