Bessie Bell and the Goblin King (Tales of Aylfenhame, book 3)
From the publisher:
The Lincolnshire Wolds, 1812. When housemaid Bessie Bell is thrown out into a cold October night, her prospects could scarcely seem worse. With nowhere to go and no one to help her, how will she survive? But on the road she meets a mysterious gentleman, and her fortunes take an immediate turn for the… strange. For the nightmare horse Tatterfoal stalks the fog-drenched Wolds, and Mr. Green is determined to catch him. But why?
Caught up in a dark adventure, Bessie is swept far beyond the shores of England and into Faerie Aylfenhame. Dangers untold await the unwary in the Goblinlands, though the greatest dangers of all may lie right behind her. For Tatterfoal answers only to his master, the Goblin King…