Lily is about ten years old and lives in an attic. Or rather, she has been kept locked there by her stepmother since her father's death. One night, she is visited by Po, a curious ghost accompanied by a creature neither dog nor cat called Balluchon. Po comes from the Other Side, where he crossed paths with Lily's father. He has a message from him for Lily… Lily is far from finished with surprises, for meanwhile, without her noticing, a young boy watches her from the street. It's Will, a young apprentice alchemist, whose master has tasked him with a high‑risk mission…