A sold-out theater at Landmark E Street Cinema housed a crowd in the nation's capital — including about 10 congressmen and their children or grandchildren — last Wednesday night for a screening of a movie with a simple premise: Choose kindness.

Wonder, based on the 2012 novel by R.J. Palacio, centers around the story of Auggie Pullman (Jacob Tremblay, Room), a 10-year-old kid who has grown up with severe facial deformities and is about to attend school for the first time. It was a book targeted at 8- to 13-year-olds, yes, but the simplicity of the story and the importance of its lesson made it something kids and their policy-making elders in the audience alike could appreciate.

"If we had filmed this movie two years ago, it might not have resonated the way I think it will resonate, just because it seems to be the right moment at the right time," Palacio said in an interview the next day. "It's a moment that celebrates the goodness of people. It's a moment that talks about differences and celebrating those differences and accepting those differences. It's a movie about tolerance and empathy. … I think now, more than ever, this movie will hopefully resonate with people and remind them about the importance of those things."

Though the book was published over five years ago and the movie finished shooting before the 2016 election, it's impossible to watch Wonder without thinking about the current political climate.

Director and writer Stephen Chbosky recalled CNN, Fox News or sometimes MSNBC playing in the break room while working with editors on post-production.

"I'd be in Wonder land and then I would go for lunch and there [was] the real world staring right back at us every day," he said. "I would walk in like, 'Oh, what happened today?' It did enter into our conversations a little bit. We thought that this story could be something of a healing experience for some folks that might need it."

And if you're making a movie about the importance of being kind, you're going to have to practice what you preach.

That's something Chbosky (Beauty and the Beast) was keenly aware of while directing Wonder — not that he had to preach very hard, given the cast consists mostly of well-known Hollywood nice guys: Julia Roberts, Owen Wilson, and Daveed Diggs (Hamilton) as Auggie's parents and teacher, respectively.

"We had a 'no yelling' policy," Chbosky said. "I said that applies to everyone, especially me, so if you ever see me cross that line, you tell me. Luckily no one ever did."

An author's involvement with his or her book's adaptation has often been an indication of its faithfulness to the source material and overall success — just ask fans of the Harry Potter series and the Percy Jackson series how they feel about the film adaptations. (Hint: Potter was a worldwide phenomenon, while only two of the five Jackson novels became films before the franchise fell through).

And Chbosky knows, maybe better than anyone, how critical an author's voice on set can be — he even directed the adaptation of his 1999 novel, The Perks of Being a Wallflower.

"I knew that R.J.'s involvement was the key to the movie's success," Chbosky said. "She created this world, we're all just kind of living in it."

"I've heard so many stories about unhappy authors in this regard, so I have to say I really lucked out," Palacio added. "I got great producers, an amazing director who really tried very hard to make me a part of the process. That was completely from his benevolence. He didn't have to do it. He could have gone a totally different way."

Aside from spending about 10 days on set, Palacio said Chbosky and the rest of his creative team kept her well-informed about decisions being made. Sometimes it was after the fact and her opinion wasn't always the deciding one, but she was "nevertheless still in the loop." Chbosky would frequently call her for advice on details: What color would the Pullmans' couch be? What kind of shoes would they wear? (Answers: yellow, and Owen Wilson rocks a pair of classic Chuck Taylors with his work suit in a way that only Owen Wilson could.)

"It's not even just a question of meeting Julia Roberts — like the world's greatest movie star — and Owen Wilson and all the cast, or even seeing how these characters that you kind of dreamed up have been brought to life," Palacio said. "But seeing all the people involved, like gainfully employed in the further bringing of life to them … It's a thrill to see all these creative people spending time trying to bring your imagination to life."

Chbosky recalled visiting Palacio's neighborhood, where she was originally inspired to write Wonder. She had been in an ice cream shop with her 3-year-old son when he saw a little girl with a severe facial deformity. He began to cry and Palacio instantly whisked him away before the girl could see his reaction. The situation left a bad taste in her mouth.

"It just got me thinking about what it would be like to face a world every day that doesn't really know how to face you back," she said. "I started writing Wonder that very night."

Perhaps the most interesting aspect of this book — and the one that made Chbosky most excited to adapt it — was the fact that it jumps back and forth between different perspectives. It begins from Auggie's point of view, but readers and viewers also get glimpses of how Auggie's life affects his sister, her best friend and Auggie's classmates.

"I think it reminds us that we're all in this book together," Palacio said. "We're all in this world together, so let's get along."

'Wonder' hits theaters this Friday, Nov. 17.