A few years ago, I paid Tommy and Joel 50 cents each to watch Mary Poppins with me. I knew they’d love it. They didn’t know they’d love it. It was the easiest bit of coin they’ve ever made. One viewing and you’re hooked. The songs, the humor, the animation, the story—all click together so effortlessly it’s hard to imagine a time when serious controversy swirled around the beloved classic.

Saving Mr. Banks tells the story of how Mary Poppins finally made it to the big screen. P.L. Travers, played fantastically by Emma Thompson, recoiled at the thought of Mary Poppins in Walt Disney’s hands. She was crisp, cold, formal. He was not. But they needed each other. She was financially strained. He made a promise to his daughter. Somehow, the two giant personalities had to find common ground.

Throughout the film, flashbacks to Travers’ childhood reveal her motivation and inspiration. Her early years were rocked by sorrow and severe shocks. She had to grow up quickly. The inspiration for Mary Poppins was her aunt, who came to help her family in a time of great need. We barely get to know the aunt because Mary, with all her wisdom, with all her magic, with all her firm discipline and love, was never who Travers lost sleep over.

It was her daddy. He’s Mr. Banks. Travers couldn’t hand over her dad to Disney because she hadn’t saved him, in the end. She had to count on a man who she found a bit loathesome to do the job. Travers was afraid of losing him twice, which was more than she could bear.

Tom Hanks plays Walt Disney. I wouldn’t like Walt Disney either if he were like Tom Hanks. I’m not sure why, but he made me squirm—and normally, Hanks can do no wrong. Was it his accent? His mannerisms? Disney comes across like an oily used car salesman. Emma Thompson absolutely outshines Hanks in every way. She was easily my favorite part of the film.

Another bright spot was Colin Farrell as Travers Goff. Yep, P.L. Travers is a pen name, inspired by her dad. I’ve never given Farrell much thought, but he was a revelation to me in Saving Mr. Banks. He captured a creative, loving spirit constrained by responsibility. Travers Goff was a free spirit stifled in a remote Australian town when he should have been the hero slaying dragons in his little daughters’ imaginations. He was a banker—like Mr. Banks.

It was fun to see how Mary Poppins came to life on the big screen through stressful meetings, late-night songwriting sessions, and tiptoeing around their temperamental muse. Travers insisted on recording everything. She had no idea what it gift it would be for future generations of Mary Poppins fans. And if you don’t leave the film humming at least one song from the Sherman brothers score, I’ll eat a carousel horse.

Saving Mr. Banks is an intimate glimpse into the life of a still-mysterious woman. It’s also an interesting peek at Disney studios in their early 1960s glory. The end seemed to tie everything up a bit too neatly, though. It left me with more questions. It’s like those old after school specials that advise you to visit your local library to learn more.

Saving Mr. Banks opens on Friday, December 20, 2013. It’s rated PG-13. Don’t make the mistake of thinking because it’s about Mary Poppins that it’s a children’s film. Alcoholism, suicide, parental death do not make for a jolly holiday with Mary. But they are thoughtfully approached, not gratuitous.

(If you haven’t, read the original Mary Poppins books. They barely resemble the Disney movie, so you can see where Travers hesitated. They are great books.)