We're still in the middle of summer blockbuster season, but the trailer for Saving Mr. Banks is one of the earliest and most promising harbingers of the fall. The film stars Tom Hanks as Walt Disney, as he attempts to convince Mary Poppins author P.L. Travers (Emma Thompson) to let him adapt her book into a feature film. "Twenty years ago I made a promise to my daughters that I would make your Mary Poppins fly out of the pages of your books!" says Disney to the skeptical author.

"I know what he's going to do to her," counters Travers. "She'll be cavorting! And twinkling!"

In addition to its two perfectly cast leads, Saving Mr. Banks features one of the most impressive ensemble casts of the year, including Paul Giamatti, Colin Farrell, Ruth Wilson, Jason Schwartzman, and B.J. Novak. The first trailer for Saving Mr. Banks seems to herald a fun and fascinating look back at the surprisingly tumultuous production of one of Disney's most beloved live-action family films — but we won't find out for sure whether or not the film lives up to its early promise until it hits theaters in December.