Kasi Lemmons’ new film, “Harriet,” depicts Harriet Tubman — the leader of the Underground Railroad and freer of slaves — as all that, but with an extra element. As played by Cynthia Erivo in an action-heavy role, she’s close to a superhero. And Lemmons intended it that way. “That was the mission,” she says. “Adventure and superheroism is inherent in the story — we didn’t want to impose it on the story. This young woman who was very small and very strong and very fast and very, very brave. That’s what we wanted to bring.”

This Harriet, in other words, looks less like the figure known from photographs taken nearer the end of life than like Erivo as the compact physical dynamo of “Widows.” The story moves fleetly, depicting both Tubman’s gift for evasion and the visions that spurred her on. “She’s kind of there and kind of not,” Lemmons says of the moments Tubman is gripped by a voice from beyond. “She has a fluid conversation [with God]; that’s the way she describes it. If you’re cynical and don’t believe that, you could say she has perfect instincts.”

Lemmons’ instincts for what will move audiences are as true; her 1997 directorial debut, “Eve’s Bayou,” inducted into the Library of Congress’ National Film Registry last year and considered a key influence on the aesthetics of Beyoncé’s visual album “Lemonade,” was critically hailed in its moment and is now widely regarded as a modern classic. But Lemmons still struggles, she says, to pull together financing for movies; “Harriet” is only her fifth feature. “I think we’ve made a little progress” since the late 1990s, she says. “Still, it’s hard. If you’re interested in women and black people, and you’re interested in drama — those things, it’s still not a walk in the park.”

Those animating loves for story and character mean that Lemmons says no to projects often. “I turn so many things down,” she says. “Directing is very, very hard. I want the money to do it, but I can’t sell out because it’s too hard a job. I need the passion to give me the adrenaline; I need the passion to give me the energy, the perseverance and the physical strength. I have to be in love, and it has to feel like love.”

For Lemmons, that feeling is visceral as much as intellectual. When told about the planned Harriet Tubman project by producers, she says, “my heart started pounding. I was afraid and I was excited. It’s like the moment you realize you’re in love. You can be next to somebody or work with somebody and you think you’re friends, and then one day you can’t breathe. That happens to me with projects — all of a sudden I can’t stop thinking about it, or I’m thinking about it in my sleep, or I wake up thinking about it. That’s how I can tell.”

In making “Harriet,” that love manifested itself through the research, finding aspects of Tubman’s personality that matched Erivo’s energy, and vice versa. Lemmons (aided by Erivo, a fellow New Yorker) stays laser-focused on character even as the situations grow increasingly hectic. “I didn’t want it to be an adventure film where the hero happens to be Harriet Tubman,” she says. “I wanted it to be the Harriet Tubman story. And so really I wanted to find her and bring her and give it some authenticity.”

Lemmons’ own story has motivated plenty of people too. “I think things would be different if it came out now,” she says, recalling the launch of “Eve’s Bayou” at a less open time in Hollywood. “But I have blazed my own trail. I’m proud of my history in the industry and what I’ve done when I’ve not been as important to people. To make that film while having just had a baby, that became very important to a lot of women.” A professor at NYU’s Tisch School of the Arts, Lemmons sees what she has been able to accomplish as a lesson that transcends the classroom. “It was pretty difficult, but I wouldn’t trade it in because it has been instructive and inspiring to other filmmakers, you know? And I’m really about that. It’s very real — I’m really, really about that.” No wonder this director was ready to tell the story of a natural leader.