Many of the best fantasy stories have some seed in the real lives of their creators. The Narnia books, for instance, came out of author C. S. Lewis’s devout Christian faith. And when his friend J. R. R. Tolkien was writing The Lord of the Rings, an epic saga about an ultimate battle between good and evil, Tolkien was likely channeling his experiences as an officer in World War I. Harry Potter probably never would have been created if J. K. Rowling’s older brother hadn’t once crayoned a lightning bolt on her forehead. (Full disclosure: one of these three examples isn’t true.)

That brings us to a new 15-minute film full of flashing swords and supernatural creatures that has its origins in a very personal story: a young British boy’s near-fatal illness. Today, Max Rowlandson is a healthy 13-year-old, but when he was only two he was diagnosed with leukemia, a deadly cancer that affects the cells in bone marrow and blood.

Like many leukemia patients, Max was treated with chemotherapy, a process in which a patient’s body is injected with powerful drugs that kill cancer cells but can also cause a lot of tough side effects, like nausea, fatigue, and hair loss. Max experienced all that and more—and his treatments lasted for a long three years. The good news is it worked. Max’s mom, Jodie Rowlandson, says he’s “full of energy” and loves to play sports. “It’s nice to see just how happy and healthy he is,” she recently told the Daily Mail.

The idea for a movie about Max came from a friend of Mrs. Rowlandson’s, Ben Pryke, who teaches film at a British college, thought the story of the boy’s fight against illness, and of the doctors who worked so hard to save him, had the makings of a terrific movie about heroes who never give up. Max’s victory over cancer “needed to be told,” Pryke said, and so he got in touch with a movie director friend, Richard Prendergast, who wrote a script and asked the Rowlandsons for permission to shoot it.

The result is a short called Maximus, which was just selected to screen this summer at the Cannes Film Festival in the south of France—a big honor, since Cannes is world’s most prestigious international movie festival. Maximus tells Max’s story through the eyes of his sister India, who wasn’t even born when he first got sick. The movie’s India, played by director Prendergast’s daughter, imagines her brother’s treatment as an epic battle with monsters, angels, wizards, horsemen, and a brave warrior hero who just won’t quit. Judging from its trailer, Maximus could give a lot of bigger-budgeted movies a run for their money.

Max, India, and their mother all have small parts, and they love the finished movie. “It was quite an emotional moment to watch it,” Mrs. Rowlandson said. “I think it’s the families that are going through the same journeys that we really want to see the film because it’s a story of hope.”

And more than hope: screenings of Maximus are set to raise money for children’s medical charities, which will help more kids end up like Max—well.

When seven-year-old Amita Suman moved to the U.K. from Nepal, she could barely speak a word of English. “I was born in a village,” Amita, now 23, says. “We lived in a house that we made of clay. We used to open fire to cook, and used horses and carriages for transport.”

But she did know one thing, and that was what she wanted to do when she grew up. “When I was in Nepal, and I was four years old, I had my first experience of TV. It was just this tiny, small thing. And someone turned it on. Somehow, we found some electricity to do it. And these people appeared, and they were acting, and they were living a life, and suddenly I was seeing new things that I had never seen before. I said to myself, ‘Oh my God, that’s what I want to do—I want to be them!’”

When Amita moved to England, she looked around and flicked through the TV channels and didn’t see anyone who looked like her. She didn’t have any connections in the entertainment industry. “I didn’t have a lot of confidence starting out,” she says. “But I persevered. I went to drama school. Again, I didn’t fit in. I was the only brown student. No one could relate to me. But the love for my craft was always the thing that was pushing me forward.”

After drama school, Amita found an agent and got a call about a new TV show. “Reading the character description,” Amita says, “I knew there and then, ‘I have to get this part, especially as an Asian actress.’”

The show was Shadow and Bone, a big-budget Netflix adaptation of Leigh Bardugo’s best-selling fantasy book trilogy. And the part was Inej Ghafa, a nimble warrior amid a crew of misfits and miscreants. Convinced she had blown her first audition—“I thought it was bloody awful because I wanted it so much”—Amita instead got a callback, and soon the role was hers.

The next hurdle? “I’d honestly never been to a gym before,” Amita says. But her character, Inej, is an expert spy. She can scale fences and leap through fire; she is sharp, strong, and moves without a trace. “So, I said to myself, I cannot respect this character if I don’t feel her strength, her stamina, her agility. I went to the gym a lot. I built so much muscle, and I felt really strong. I felt capable.”

Shadow and Bone is out now on Netflix