Nicolas Mejía, a 22-year-old D.J. from the Cypress Hills section of Brooklyn, had been spinning records in small clubs around New York for just under a year when a call came in from a much larger venue. Elsewhere, a huge club in Bushwick, was hosting the latest installment of Sksksks, its traveling hyperpop dance party in August, and its organizers wanted the D.J. to perform the opening set.

Elsewhere is a sprawling complex that has hosted big-name experimental pop artists like Sophie and Kim Petras — this particular party would bring six up-and-coming acts to the venue’s main hall. But when the complete roster of D.J.s dropped on Instagram in the days leading up to the party, Nicolas Mejía, who performs as D4rkcircles, noticed that one particular artist on the lineup, a newcomer to the Brooklyn electronic scene, was generating more buzz than any of the other performers combined.

Who was Chelsea Manning, the D.J. wondered, and why was everyone talking about her?

It wasn’t a stage name: Chelsea Elizabeth Manning, the former Army intelligence analyst whose leak of hundreds of thousands of classified documents detailing U.S. military operations in Iraq and Afghanistan earned her a 35-year prison sentence (commuted after a presidential intercession), is indeed a D.J. And late Friday night, clad in light-up cat ears and tinted sunglasses, Ms. Manning played an hour of fast-paced dance music to a throng of writhing partygoers, some of whom were unaware that the D.J. blasting Britney Spears remixes had spent years of her life in a maximum-security military prison for disclosing secrets of U.S. military campaigns in the Middle East.

“There’s a large population of the world, or at least this country, that disagrees with what she’s done,” said David Chan, who created Sksksks. “But from my perspective, she’s a national hero.”

Mr. Chan — a party promoter and D.J. better known in New York nightlife circles as Thelimitdoesnotexist — said he hadn’t been aiming to make a political statement by inviting Ms. Manning to play at Elsewhere. While brainstorming potential artists for the Sksksks party, which is geared toward queer and trans partygoers, Mr. Chan stumbled across a 2018 article published in The Outline in which Ms. Manning (who is transgender) revealed her background in D.J.ing and electronic music production.

Unsure whether she would respond, Mr. Chan messaged Ms. Manning on Instagram to ask whether the former army intelligence analyst would be interested in returning to her raver roots. “My art is booking an act people talk about,” Mr. Chan said. “There was something about it that was funny, and really cool.”

To Mr. Chan’s surprise, Ms. Manning replied. She was in.

Hours before Ms. Manning pressed play on her first track of the night, Mr. Chan (who also performed) was scuttling around Elsewhere, tweaking feedback on microphones and fussing with strobe lights. Bass thumped like thunder in the empty, cavernous hall, then cut out — technical difficulties.

Around 10:30 p.m., attendees started trickling in, sporting furry leg warmers, mesh tops and elf-ear prosthetics. Some partygoers made a beeline for the dance floor, where they immediately began thrashing to a remix of “How to Save a Life” by the Fray. Others, like Miles Raymer and Callie Richards, a couple who said they had ended up at the rave “kind of by accident,” decided to people watch from the smoking section until Ms. Manning came on at midnight.

“We kind of thought it would be a funny thing to do on our way home from our date in the city,” Ms. Raymer said.

Ms. Raymer, a trans freelance music journalist and critic, has attended raves since the 1990s, but she said she found the event a little strange. “This whole party is really giving internet people IRL,” she said. “There’s a certain kind of awkward coming-out-from-behind-the-screen sort of energy. If you spend a lot of time on social media with a lot of trans girls, there’s a certain kind of nerdy, internet-steeped girl who is very much in the building tonight.”

Thomas Wynne, a veteran Sksksks attendee who sat perched on Elsewhere’s staircase, concurred with Ms. Raymer’s assessment, adding that the party felt a little more “Reddit” than normal.

“It attracted a different clientele from the usual event,” Mr. Wynne said. “If you look at the crowd, you can kind of tell who’s here for Chelsea Manning. Not in a bad way, but it stands out.”

James Ko, an associate creative director in Bushwick who was wearing bright pink boots, was one such attendee. “I love Chelsea,” Mx. Ko said. “I literally wrote her fan mail when she was in jail and everything, so I definitely wanted to support her for her first D.J. event.” (According to Ms. Manning’s Twitter account, Friday night’s event was her first D.J. gig in 15 years.)

Mx. Ko, who is trans and nonbinary, sees Ms. Manning’s life as a story about perseverance on the margins. “She’s a big inspiration in terms of getting out there and living a life that’s defined by her transness but not solely by her transness,” Mx. Ko said. “Her journey is kind of a microcosm of the trans experience. We all go through our own stuff, but to think about being in that kind of isolation and confinement — I think a lot of trans people can identify with that.”

For Ms. Manning, it was a long road back to the dance floor. She was initially arrested in 2010 after providing WikiLeaks, the online intelligence organization founded by Julian Assange, with classified material that included footage of American soldiers chuckling after fatally firing at several civilians, including two Reuters journalists, in a 2007 helicopter attack in Baghdad.

Convicted in 2013 on charges including six counts of violating the Espionage Act and sentenced to 35 years in prison, Ms. Manning spent six years at Fort Leavenworth, a men’s military prison in Kansas, where a struggle to secure gender-affirming care behind bars took a significant toll on her mental health. (Ms. Manning tried to end her own life twice while incarcerated at Fort Leavenworth.)

In 2017, President Barack Obama commuted all but four months of Ms. Manning’s remaining prison sentence, an act of clemency sharply criticized by several prominent Republicans at the time. She was jailed again, for 10 months, in 2019 for refusing to testify before a grand jury investigating WikiLeaks.

At Elsewhere, however, not everyone was aware of Ms. Manning’s extraordinary journey to the Bushwick nightclub. Passing through the rooftop bar, a group of men attending Elsewhere’s other party that night could be overheard explaining Ms. Manning’s significance to one another. (“So she’s, like, Julian Assange? It’s like if Assange was D.J.ing right now? I’m there for it.”)

Around 12:30, the crowd erupted as Ms. Manning stepped into the D.J. booth. Over a pulsing beat, a disembodied voice intoned: “What is reality? Can you describe your way to joy and connection? What is love? Show me love. Tonight, in this house, we begin the third summer of love.” When the beat dropped, the dance floor let out a collective yowl as the music picked up speed.

Ms. Manning played Charli XCX. She played drum and bass. She remixed the theme music from the HBO show “Succession.”

“I had a feeling that she was going to play transgirl-video-game-nightcore-hyperpop music, and it kind of delivered,” said David Yoakum, a partygoer who was there to support a D.J. who performs as Swan Meat, scheduled to close out the night. “I think it was great.”

Backstage in the green room, Ms. Manning had gained a new fan. “She was so good,” D4rkcircles proclaimed. “Major queen.”

As the red digital clock on the D.J. booth ticked past 3 in the morning, Swan Meat, dressed in an anime-printed bodysuit, was having a cigarette to ready herself for her set. “It’s really cool to be part of a burgeoning scene, post-Covid,” she said through tobacco smoke. “I may be playing to an empty room as people clear out, but it’s still fabulous.”