In 1928, Lielle Chevalier, an 11-year-old girl, resides at Château Trois Grâces, a hotel owned by her family and managed by her Uncle Gabriel. She’s been sent there by her parents who are at odds with Gabriel over hotel management.
An indoorsy child, Lielle explores the hotel’s attic to keep entertained. There she encounters half-forgotten boxes of old belongings. Gabriel, finding her there, authorizes her to rummage but cautions against removing valuables.
For days, Lielle keeps herself amused by trying on old clothes stored in the boxes. She then finds an unopened box which contains a large moonstone pendant and a handwritten book in Cyrillic. She brings these items secretly to Artur, an old Russian beach-librarian who’s familiar with the language. Initially reluctant, Artur’s interest is piqued upon scanning the Cyrillic book. He promises to translate and reveal the text to Lielle in three days.