American swimmer Gertrude “Trudy” Ederle was just 20 years old when, on Aug. 6, 1926, she became the first woman to swim the English Channel. Only five men had accomplished the feat before her, but her time was better than all of theirs; at 14 hours and 31 minutes, it was nearly two full hours faster than the previous record-holder. It was a record that stood for 24 years. A new film about the achievements of this amazing but forgotten athlete—based on Glenn Stout’s 2009 biography, Young Woman and the Sea, and starring Daisy Ridley—premieres in select theaters on May 31.

Stout’s book efficiently runs through the highlights of Ederle’s first 20 years, while weaving in a brief but detailed history of how swimming became the sport we know today. He points out that it was rare that American women were taught how to swim at the turn of the 20th century, as it was deemed a dangerous and even immoral activity. When the passenger steamboat General Slocum caught fire and sank in New York City’s East River in 1904, most of the passengers onboard were women and children who lacked the ability to swim to shore; as a result, more than 1,000 of the boat’s 1,342 passengers died. The tragedy inspired many American families to teach their children how to swim, which helped to popularize it as a recreational activity—particularly among women.

Ederle was one of those new swimmers, despite concerns that the activity could worsen her partial deafness, the result of a bout of measles. She and her family lived not far from where the General Slocum disaster took place; her father ran a butcher shop on Amsterdam Avenue on Manhattan’s Upper West Side, and she learned to swim, along with her siblings, in nearby New Jersey. She later joined the local Women’s Swimming Association and learned the latest strokes, including the American crawl, which emphasized speed. Ederle immediately took to the sport and was such a natural talent that she achieved her first world record at the age of 12—the first of many records she would set over the next few years. She went on to medal multiple times in the 1924 Olympics, when she was just 18. She soon set her sights on the English Channel crossing; her first attempt in 1925 failed, likely due to sabotage by her swim coach, Jabez Wolff, who’d never successfully swam the Channel himself. (Stout makes a strong case that Wolff didn’t want Ederle, whom he disliked, to succeed, and that he may even have poisoned her to ensure she’d become ill during the swim.) She tried again the next year with a new coach—Bill Burgess, who, in 1911, was the second man to swim the Channel. This time, Ederle succeeded, and she came home to New York a hero, ticker tape parade and all.

The film adaptation of Stout’s book sometimes plays fast and loose with details for dramatic effect or to streamline the storytelling. For example, it gives Ederle just two siblings, instead of five, and it portrays her experience in the 1924 Olympic Games in Paris as a flop when, in fact, she won a gold medal and two bronzes. It also has her making her second attempt to swim the Channel almost immediately after her first, when, in reality, the two events were separated by more than a year.

The list goes on, but to complain about these things seems pointless, because the film gets so much else right. It very accurately showcases Ederle’s unbelievable talent, as well as her impressive, unflagging self-confidence. She set out to accomplish amazing things, and she simply did them—she didn’t second-guess herself, and she didn’t listen to the many naysayers around her. Nor does the film play down the pervasive sexism of the era, which Ederle encountered almost everywhere she went. In one affecting scene, Ederle’s sister, Meg (excellently played by Tilda Cobham-Hervey), angrily laments, “They don’t want us to be heroes. They don’t want us to be anything.”  Against such a backdrop, it’s impossible not to be moved by Ederle’s fierce drive to be the hero that men in power don’t want her to be—her desire to be everything.

Director Joachim Rønning, cinematographer Oscar Faura, and production designer Nora Takacs Ekberg provide a suitably grand stage for this story. Their vision of New York City in the 1910s and ’20s is gorgeously detailed and feels impressively authentic, while Amelia Warner’s lush score gives the narrative the feel of an epic. None of this would work, of course, without the considerable talents of Ridley, who effortlessly inhabits her character, and the supporting cast—particularly Christopher Eccleston as the petulant Wolff and German actor Jeanette Hain as Ederle’s no-nonsense mother. Does the movie get every detail of Ederle’s story right? No. But does it understand that story’s importance and make the audience feel it? Absolutely.

David Rapp is the senior Indie editor.