The Princess and the Goblin. by George MacDonald

The Princess and the Goblin is a children's fantasy novel in the vein of the best classic fairy tales. The simple narrative follows Princess Irene as she discovers a ghostly relative living in a castle tower only she can access. During a walk outside one day, she encounters the threat of the lair of goblins living near the castle-and meets a new friend, a young miner named Curdie. She and Curdie must stop the goblin threat before they can carry out their evil plot.