No Prep Module: A Flayer's Feast (Patreon)

https://www.kassoon.com/dnd/adventure/no-prep-module-a-flayers-feast/ 

An alhoon is a mind flayer that has discovered the arcane arts. Exiled from their colony as deviant minds, they are loner outcasts that can never return to the brood or join with an elder brain. One such alhoon has made its lair in the sewers underneath the town of Princemell, and has developed such a refined  palate that only young brains will sate its hunger. The alhoon has been abducting children from their homes at night, and the problem has grown large enough that the town's parents are desperate for help.

https://www.kassoon.com/dnd/adventure/no-prep-module-a-flayers-feast/