The Doom-Cave of the Crystal-Headed Children (DCCHC) was the Free RPG Day release for the Lamentations of the Flame Princess RPG. If you were really lucky, your FLGS isn't run by a douchebag who refuses to carry LotFP products and you got a print copy earlier this year. Unlucky souls can still pick up a pdf copy of the adventure. DCCHC was initially funded on Indiegogo and that is the only way I was able to procure a print copy of the module.
James Raggi IV has a reputation for writing adventure modules that are basically traps for the PCs. Another blogger coined the term negadungeon to explain this kind of module, an adventure that is meant to destroy the PCs rather than to entertain or reward. I personally find assessments like this unfair, but I will say that he manages to craft adventures which seem uncompromisingly difficult from a cold reading.
The premise of DCCHC all by itself is weird and horrifying. All of the women in a small town are convinced that they gave birth to a son four years ago, named him Andrew, and yesterday he disappeared - despite the fact that nobody else remembers these multitudes of Andrews and there is no evidence that these Andrews exist except as a mass hallucination of the women of this town, one of these boys is seen outside of town, and... you'll have to read the adventure or play through it to find out who and what these Andrews are.
Having read that last paragraph, aren't you intrigued to find out what is going on? I know I was!
DCCHC is a great module because there is a ton of weird and dangerous stuff inside a dungeon complex that is authentically creepy and strange, but the real charm of this adventure is that the main hook that brings the PCs to the cave could all be resolved in the very first rooms. The plot involving the many Andrews takes up about 6 pages of a 36 page adventure. Everything else around the crystal-headed children is just icing on the cake!
Even though it was a Free RPG Day offering, you can still get "The Doom-Cave of the Crystal-Headed Children" for free (or purchase it as a pay-what-you-want pdf) at DriveThruRPG