Mark Baumer was a sensitive soul — with very tough soles.

The writer/environmental activist decided to take a break from his job at Brown University in Providence to film himself walking barefoot across America. He started his journey in October 2016, hoping to bring awareness to the global threat of climate change and raise money for the activist group FANG (Fighting Against Natural Gas) by simply posting it all on YouTube in real-time.

But his videos drew the attention of acclaimed Pittsburgh-based filmmaker Julie Sokolow, who became fascinated with Baumer’s quixotic quest. Her film, “Barefoot: The Mark Baumer Story,” will be screening at the Three Rivers Film Festival on Nov. 16 at the Regent Square Theater.

Sokolow excels at empathetic portraits of fascinating individuals.

Her movie “Woman on Fire,” about the first openly transgender firefighter in New York City, brought her national attention.

Her films “Aspie Seeks Love,” about a talented writer with Asperger syndrome and his quest for connection, and “Street Doctor” — about a doctor who dresses like a homeless person and spends long nights treating the forgotten denizens of Pittsburgh’s streets — featured local subjects.

Though Baumer’s journey was national, this film is in many ways also a local effort: Sokolow was the recipient of an “Investing in Professional Artists” grant of $35,000 from The Pittsburgh Foundation and The Heinz Endowments, as part of a residency hosted by Steeltown Entertainment.

“Barefoot” just won the Best Premiere Documentary Feature Award at the Heartland International Film Festival in Indianapolis. Here’s how it came to be:

Julie Sokolow at the Heartland International Film Festival. Photo by Whitney Walker.

“We had some mutual friends, and they would post about him on Facebook; I saw his YouTube videos,” explains Sokolow. “It became something I looked forward to every day. As a filmmaker, I really admired his courage to just go out there with a camera by himself on the road, filming himself, everything he saw, people he met. Meanwhile, he’s doing this athletic feat of walking barefoot on the road.”

The intense, bespectacled Baumer is an incredibly charismatic character. He talks to cows in a pasture. He talks to puzzled passersby. He talks to his own feet. He blurts out things like, “Penguins are going to go extinct! I don’t want to live in a world without penguins!”

“Barefoot” poster. Courtesy of Julie Sokolow.

Nature seems to bring him the most intense joy, but he narrates even the most mundane occurrences as though they’re totally new and exciting. He delivers impassioned soliloquies about the peril of climate change. He seems incapable of boredom.

His journey began “at the time of climate-catastrophe Donald Trump’s rise to power,” says Sokolow. “Mark just seemed like a symbol of hope, for me.”

Donald Trump’s inauguration, she says, was “kind of a dire moment for a lot of us who were worried about his presidency. I immediately turned to one of Mark’s videos for comfort and reassurance, and that’s exactly what I found. On the day of the inauguration, he gave his most passionate speech about what Donald Trump represents and how we need to keep fighting. I felt encouraged by Mark to keep going and not fall into despair.”

Baumer was busy on the road writing and editing videos on his phone, and newspapers had begun writing about him as people all over the country followed his progress.

“His childlike wonder, his unique sense of humor appealed to me,” says Sokolow. “Also, his fearlessness. Mixing that all together creates a really compelling combination. You’re watching him and he seems so uplifting and happy and funny, and then you have to almost stop and realize, he’s doing something really dangerous — cars are constantly whizzing by. You see a tension between his joyful persona and the danger that he is in, and the sacrifice he’s making to bring awareness about climate change and the environment.”

Sokolow was eagerly following the progress Baumer made as the fall of 2016 gave way to winter. When Baumer got to Ohio, the ice, salt and chemicals on the roads took their toll on his unprotected feet. He decided to take a detour to Florida, to restart on a southerly route. Rejuvenated by the warmer weather, he continued his walk.

Then, “I started to see people posting, ‘We’ll miss you forever Mark’ and started thinking, ‘What does that mean?’” Sokolow says. “I quickly started to realize that he had died. Even having never met him before, I felt close to him through his videos.”

Baumer’s story is, ultimately, a tragedy. He was struck by an SUV on a road in Florida.

“It felt really symbolic somehow,” she says, “with Trump being inaugurated and Mark dying the next day — and his last video addressing this — that dark times were ahead.”

Baumer had planned his journey with care and knowledge, Sokolow says. He had walked across America successfully in 2010 in just 81 days wearing shoes.

“His feet were fine! He had actually studied barefoot running, and worked and trained to build his feet up,” she says. “This was not just a whimsical endeavor. He wore a bright orange reflective vest and stayed in the shoulder. He was mindful of his safety.”

Sokolow’s powerful documentary explores Baumer’s journey, which is interspersed with videos of Baumer growing up and conversations with his loving parents, who have started a nonprofit fund to keep his memory alive and continue his work.

They are flying in from Maine for the screening in Pittsburgh.