I’m trying to find a book I read many years ago. It’s about a boy/guy who goes to work for a mill where strange things happen - people use magic and stuff. Like, one man traces a symbol/rune in the air, and the room’s dust is cleaned. However, the boy/guy realizes that more sinister stuff is happening - people who work and live in the mill are being killed/sacrificed.
I remembered “satanic mill” because that’s what a friend told me the book was about, but it is almost definitely not the title.
It seems that the original title of the book was “Krabat”, and the translation is called “Satanic Mill”. According to the reviews, it’s pretty much like you described, with the sacrifices and all, but I’m not too sure about the runic symbols.
WeRSauron, I remember that book. If we are talking about the same one, Hot Buttered Toast has got the link to it. I always remembered the title as being The Satanic Mill. It may still be available at a local library.