Lilly, a 10-year-old girl, is celebrating her birthday. Her parents decide to take her to a fair to mark the occasion. In the crowd, Lilly gets separated from her parents and finds herself in front of a huge mysterious palace. At the entrance, she is welcomed by Mr. Hotchpotch, the guardian of the place.

Surprised to see a child alone, Mr. Hotchpotch invites Lilly to explore the Musical Palace. This magical place is full of treasures: relics from the greatest shows, music hall, cabaret, and cinema. An incredible adventure begins.