The Satanic Mill

Deutscher Jugendliteraturpreis (Prize for Literature for Young People) 1972.

The original novel was published in 1971. Also known as The Curse of the Darkling Mill and Krabat. Translated by Anthea Bell. Information from Wikipedia: "The English translation first was published as The Satanic Mill from 1972 to 1991, then republished in 2000 as The Curse of the Darkling Mill and in 2011 as Krabat."

Secret Arts. Unexplained deaths. What is happening at the mill in the fens? Drawn by powers beyond his control, fourteen-year-old Krabat finds himself apprenticed to the dark mill and begins work with the Miller's eleven other journeymen. But strange things continue to happen at the mill. Time passes at an unnatural pace, and the journeymen have superhuman powers, and can turn themselves into ravens and other creatures. Trapped by an evil power which makes escape impossible, Krabat is forced to submit to the Master of the Mill as he tries to unravel the mill's secrets. "The Curse of the Darkling Mill" is an eerie tale of sorcery and nightmares, which will keep you guessing right to the end.