Zosia lived above her grandfather's small bookshop. Inside it smelled of paper and cinnamon. Outside the window, rain splashed and silvered the street. Grandpa was arranging books and Almond the cat was taking a nap. Zosia was cleaning the shelves and singing a quiet song. Suddenly a book with a blue cover with stars fell down. Between the pages lay a silver key, warm as a bun. A small crescent moon and star glittered on the spine. A notebook-sized door shimmered at the back of the bookcase. A hole in the shape of a moon and waves was visible. "Do you hear that?" whispered Almond, suddenly very attentive. Zosia put the key down and heard a quiet clink. A breeze blew, although the windows were tightly closed. The air smelled of salt, cocoa and a warm night. A bell sounded behind the door, and something knocked. "Sophie, hurry up," whispered a shell-like voice. The door vibrated, light spilled across the floor....