George MacDonald 
Princess and the Goblin [EPUB ebook] 

The enchanting story of The Princess and the Goblin, brilliantly introduced by Ursula Le Guin, author of the Earthsea quartet. Princess Irene lives in a castle in a wild and lonely mountainous region. One day she discovers a steep and winding stairway leading to a bewildering labyrinth of unused passages with closed doors — and a further stairway. What lies at the top? Can the ring the princess is given protect her against the lurking menace of the boglins from under the mountain?