It's 1919. Henry has moved to the countryside with her parents and her baby sister, Piglet - all still scarred by the death of her brother.
Alone in her head, she begins to explore her surroundings, encouraged by her only friends - characters from her favourite books. Nobody much notices when she wanders into the woods at the bottom of the garden and meets Moth, a striking witchlike woman. Together they form a bond that could help Henry save her family.