The Ocean at the End of the Lane by Neil Gaiman
This is a magical little tale, told from the perspective of a young man remembering his childhood, when he befriended a strangely ageless young girl living in a farm at the end of his lane. She — and her mother and grandmother (maiden, mother, and crone) — keep slippery and dangerous things from other realms at bay. However, one of these beings slips through (partly due to the boy’s actions), and it begins to make his life a misery.
I sped through this book, partly because it is quite short, and partly because the plot and the characters drag you along for the ride. It evokes a lot of feelings from childhood — particularly of powerlessness in the face of the actions of adults — but also that feeling that everything is possible.