Joe Ballarini has sold a lot of spec scripts. But Skyward, the spec he sold recently to Fox, may be the most consequential one yet. Every writer has that “one special story that you keep in your heart,” says Ballarini. “And this is one of them.”

Based on a true story, Skyward tells the incredible tale of two East German families who escaped over the Berlin Wall by building a hot-air balloon in their garage. Ballarini fell in love with “this remarkable story of escape and rebellion and the search for freedom without the use of weapons.”

Constructing a hot-air balloon is harder than it might seem. To see one inflate up-close is to witness an eight-story-high behemoth rise from the ground and take flight. The families had to acquire enough fabric to cover two-and-a-half basketball courts. “They didn’t want to be found out,” Ballarini reminds us. “You couldn’t exactly just go and grab these miles of clothing that were required for it. So they had to go and get different clothes from different department stores.”

Add to this the fact that there were no hot-air balloons or balloon companies in East Germany. The two families—led by electrician Peter Strelzyk and bricklayer Gunter Wetzel—learned about propulsion systems, aerodynamics, and viable materials by trial and error. Some of the errors forced them to start over with a new balloon.

“It’s pretty incredible for them to have done this without ever actually seeing one in person, without ever actually having flown in one.” Their courage moved Ballarini profoundly; their anger at their government’s intrusion on freedom and privacy, their yearning for a better life. On the flip side, Ballarini could also relate to the families’ nagging worry that their situation wasn’t worth the risk. “I think I’m brave writing a spec screenplay. They’re making a spec hot-air balloon.”

If a script centering on a border wall seems well-timed, it’s because it was not an accident. Ballarini began looking into East German escape stories “about a year-and-a-half ago, when the election started rising and there was mention of a wall.” Though he was excited by the story, work and life took over, and the screenplay sat unfinished for most of the year.

But during the annual Hollywood lull around Christmas, and with a newborn at home, Ballarini rediscovered Skyward with a more urgent perspective … a father’s perspective. “I connected to this story on a visceral level of wanting to protect your family and going to such great lengths to protect them.”

Halfway through the script, Ballarini realized that Disney had made a similar film starring John Hurt and Beau Bridges over 30 years ago, Night Crossing. Nearly every writer has experienced that particular panic upon discovering that someone else had the same idea. But Ballarini’s lawyers assured him that, because it is a true story, he was in the clear, and the writer forged ahead.

Dramatizing a true story is tricky business, especially when one doesn’t have the opportunity to get to know the people who lived it. Ballarini strove to be true to their spirits, looking for goalposts along the way to inform him of where his characters might have found themselves emotionally. For instance, a footnote that Peter’s son had to take over and help build the rig let Ballarini know that the children, for their own safety, had been kept in the dark. “That moment when he says ‘I need your help’ is a great father-son moment.”

Don’t expect Peter and Gunter’s wives to be hovering ineffectually in the shadows. “I didn’t want this to be, ‘It’s two men doing daring things, and their wives were terrified the entire time.’ The only way you could pull something like this off is to have an incredible life partner.”

The writer’s relationship with his own wife, and the strength he witnessed in her through pregnancy and childbirth, strongly influenced his depiction of Doris Strelzyk. Doris partners with husband Peter in the risk and responsibility, double-checking calculations and doing quality control. Ballarini didn’t want the wives to “just be the wives. I wanted them to really be the companions and the ones who were also driving this train … in a fun way, they’re fighting to be the main characters themselves.”

Known more for writing family adventures (My Little Pony) or paranormal scripts (Dance of the Dead, The Residence), Ballarini is not keen on message films. “It feels very medicinal, to use my producer Karen Rosenfelt’s words,” he explains. And a recounting of a historic event can easily fall flat emotionally, zeroing in on facts and timelines and neglecting the spiritual center.

But with Skyward, the scribe found a voice he has never been comfortable expressing before, one he realizes now has been lurking within him for some time. It’s a voice that is “a lot angrier, a lot more urgent, a lot more paranoid, but couched with a need and a desire for freedom, hope and inspiration.

“I said some things in this script that I don’t normally say.” When Skyward went out, Ballarini worried that this newfound rawness might spark negative reactions. A big plus about writing fantasy, he muses, is the ability to hide: “‘That’s not the way I feel. That’s the way a blue orc feels … Oh, no, I’m not talking about that, I’m actually just talking about the politics of being a pixie.’”

In the end, though, Skyward was a story that simply would not let him go. And, judging from the ardent response so far, Ballarini’s impassioned rendering of it will connect deeply to many.

In Part II, we’ll talk more with Joe Ballarini about his career, the business, and his views on the craft.