Some Joan Aiken books are perfect for when the days get colder and shorter, and this is one. Abandoned impoverished orphans thrown out into the the cold and the snow to survive while surrounded by villainy. In this case it's Lucas and Anna Maria, under the guardianship of the horrible Sir Randolph, who owns a particularly dark and satanic mill in the dark and satanic town of Blastburn. Lucas and Anna Maria seek employment, not too hard to come by since child labour is all the rage, the more disgusting and dangerous the better, and find themselves in deadly danger from a couple of different sources. Will they survive? Will they find a measure of comfort and security and love? Is Blastburn just too horrible to save, and most of the people in it likewise? A great read, full of the usual dark invention and strange horrors and homely delights.