Thirteen-year-old Stella is not like other girls. She helps dad with the flower shop, her chatter in her mother's native language makes the plants grow stronger, and the girl understands what azalea is sick of at a glance. One day, Stella meets a man in a top hat who claims that she is a plant charmer, and her mother should have left her the key. The girl doesn't believe him, but... There really is a key in the attic. How did it end up in Mom's things? Stella decides to keep the find to herself. The next day, the girl walks home from school with the new kid, Kian. They chat sweetly until the boy offers to open the door with a key from the attic. It turns out that Kian was sent by a man in a top hat! Stella finds herself in a magical world of caves with strange creatures and inhabitants. Will she be able to return home? And why can only a plant charmer find a star flower?