Thirteen-year-old Bertie strives to save Theater Illuminata, the only home she has ever known, but is hindered by the Players who magically live on there, especially Ariel, who is willing to destroy the Book at the center of the magic in order to escape into the outside world.

In the old grand piano at the Ballet Jolie in New York City lives a ballet dancer who just happens to be a mouse, and who intends to become principal dancer in ballets for mice and humans, and the occasional dog, as well.