A few days before Christmas in 2020, quarantined with Covid in the basement of a Hare Krishna ashram in Philadelphia, Justine Payton admitted to herself how bad things had gotten.

She was 28 years old and had $72 to her name, after spending years working seven days a week in a cycle of cleaning, cooking, teaching, worship and selling books on the street. She rose at 4:30 each morning and her days ended at 9:30 p.m. If she violated the home’s strict rules — sneaking a piece of chocolate, say — her fellow devotees would report her to their leader, whom they knew as Mangal-arti.

Ms. Payton had moved to Philadelphia to help open the Mantra Lounge meditation center at the behest of Mangal-arti’s “spiritual master,” Devamrita Swami, a New York-born, Yale-educated leader in the Hare Krishna movement. The responsibility was an honor, she believed at the time. The movement had given her joy, purpose and community when she desperately needed it. Now she was reaching new followers with the same things that first attracted her: cheap yoga and vegan meals, and then meditation, chanting, and volunteer work.

But over time, the experience soured into something she would later describe as emotionally and spiritually abusive. Although she was bringing in money for the center through book sales, she kept none of it, she said, and had to use her savings to pay for some toiletries and other necessities. After Mangal-arti, who had no formal medical or psychological training, told her she had borderline personality disorder, she said, she had begun to doubt her own instincts about even the most basic facts of her existence, doubts that reflected Hare Krishna teachings about not relying on one’s own emotions. (Mangal-arti, whose legal name is Aarti Khoda, said in a statement to The New York Times that she did not make a diagnosis, but inquired whether Ms. Payton might have the disorder because of her “extreme behavior.”) Ms. Payton contemplated taking her own life. She was paranoid, lonely and very, very tired.

Ms. Payton didn’t think of herself as part of a larger story about the popularity of alternative spiritual practices in the splintering religious landscape of 21st-century America. She hadn’t yet parsed the borderlines separating willing self-abnegation, mental illness and abuse. She craved transcendence, and like an increasing number of Americans, she didn’t find it in Christianity or another historic monotheistic religion.

She found it instead in a much younger movement that, for previous generations of Americans, conjured hippie freedom or cult conformity. For her, though, those associations were long in the past. The Hare Krishna movement seemed to answer her deepest questions. She was a seeker, and for a while, she had found what she was looking for.

When she got sick in the first year of the pandemic, however, the basement quarantine was the first time in five years that she had been alone for a sustained period of time. It was the first time she had time to think.

She picked up the phone and called her dad.

Ms. Payton was raised on a leafy downtown street in an affluent suburb of Chicago. She was close to her parents and her three siblings. When the children were little, the family had dance parties in the house. Ms. Payton would toss her hair around to the “Be-In” song from the musical “Hair”: “Hare Krishna, Hare Krishna,” she would sing. “Beads, flowers, freedom, happiness.”

She was baptized into the Roman Catholic Church, from which she imbibed the lesson that a large religious institution could have ugliness in its past, but still do good in individual lives. Her family later joined the United Church of Christ, a liberal Protestant denomination. In an essay she wrote for a confirmation class in eighth grade, an experience meant to usher her into adult faith, she wrote that she wasn’t sure she believed in God. Ms. Payton’s highest value at the time was independence. She moved across the country for college, then took a semester off and lived in Rwanda.

She was about to leave for a study-abroad program in France when she came down with Guillain-Barré syndrome, a disorder in which the body’s immune system attacks its nerves. She was temporarily paralyzed from the neck down. She had climbed Mt. Kilimanjaro, and now she lived at home in the suburbs and couldn’t feed herself.

She turned 21 during her convalescence, and the radical loss of control made her question everything. She began thinking about what it meant to be separated from her own physical existence.

She read and reread “Siddhartha,” Herman Hesse’s novel and a defining text of 1960s youth culture. The story follows a man in India seeking spiritual enlightenment in the time of the Buddha.

“What is meditation?” the protagonist asks himself. “What is leaving one’s body? What is fasting? What is holding one’s breath? It is fleeing from the self, it is a short escape of the agony of being a self.”

She recovered from Guillain-Barré and decided to finish her college degree in New Zealand. There, an acquaintance passed along a flier for a Sunday feast at a Hare Krishna temple. Ms. Payton knew little about the Hare Krishna faith, beyond those childhood days of twirling around to music from “Hair.”

The environment she walked into that Sunday seemed made precisely for her. Since the 1990s, the movement has attempted to appeal more directly to Westerners.

The Hare Krishna movement evolved from a 16th-century Indian tradition, and exploded as a worldwide phenomenon when a charismatic Hindu guru known as A.C. Bhaktivedanta Swami Prabhupada arrived in the United States in the 1960s, attracting crowds of young people to Tompkins Square Park in Manhattan with his chanting and his saffron robes. He called the movement the International Society for Krishna Consciousness, or ISKCON.

His timing was impeccable, meeting a counterculture primed to embrace ISKCON’s practices of communal living, ecstatic dancing and asceticism. Within five years, the chant “Hare Krishna” was everywhere: among throngs of devotees proselytizing in airports; in “Hair”; in a No. 1 hit song by George Harrison.

The first wave of American followers were mostly white, but over time the movement became more Indian American and less high-profile. By the 1980s, it was beset by scandals, including lawsuits over sexual abuse and accusations of “brainwashing.” In the late 1990s, the movement’s own official journal exposed widespread physical and sexual abuse of children at Hare Krishna boarding schools.

Some American followers still live at ashrams — the standard form of membership in the 1960s and ’70s — but many more have typical homes and jobs and attend services on weekends. A spokesman, Anuttama Dasa, estimated that ISKCON currently has roughly 100,000 fully initiated members around the world, and 15 million who attend meetings.

“There’s very few Western, American people that are joining the Hare Krishna movement today,” said E. Burke Rochford, a professor emeritus of religion at Middlebury College who has studied the faith for decades. “Yes, they’re interested in yoga and yes, meditation, but not in what ISKCON is requiring of their members.”

There is a sense of urgency among the aging first generation of devotees, he said, to recapture the imagination of younger white Americans — not to push out Indian immigrants, but to preserve Swami Prabhupada’s calling to reach non-Indian young people.

The center Ms. Payton wandered into in New Zealand in 2014 was headed by an American-born guru named Devamrita Swami, who has a mission to attract “Westerners,” meaning non-Indians.Devamrita Swami’s innovation was that ISKCON should be what the scholar Nicole Karapanagiotis has described “an edgy meditation- and mindfulness-based social club.” Instead of temples with elaborate statues of Hindu deities, he opened “lofts” and “lounges” where Hindu imagery is minimal. He encouraged programming on environmental sustainability, rebranding ISKCON theology’s emphasis on giving up material pleasures as a tool for addressing climate change.

“You felt like an honored guest when you walked in there,” Ms. Payton recalled in an interview. “The whole thing was kind of ethereal and captivating.” There was a vegetarian meal, music, incense and yoga. She started attending and volunteering regularly, and a few months later she moved into an ISKCON ashram in Wellington, New Zealand.

At the end of 2015, Devamrita Swami encouraged Ms. Payton to help Mangal-arti start an outreach program in Philadelphia.

Before she moved there, she went to Illinois to spend a few weeks with her parents, Dean and Lisa, who had initially been accepting of her entrance into the movement. They understood that the Hare Krishna faith spoke to their daughter’s compassion, as well as to her interests in climate change and veganism. By this point, however, they were becoming concerned.

“She had lost her autonomy,” Mr. Payton said. “Her tone changed, her bearing changed.”

“Where did Justine go?” Lisa Payton wondered.

Her witty, vivacious daughter now rose at 4 in the morning to chant, and spent all her time cooking, ceremonially offering each meal to the deity Krishna before allowing her family to eat. Her voice was getting softer, almost melodic.

Lisa tried to understand. Picture a mountain, a pastor at her church would tell her later. God is at the top, and Justine is on one of many paths up the mountain. But it felt as though her daughter’s path was leading her farther and farther away from her family, and from any semblance of the life they had imagined for her.

When Ms. Payton left for Philadelphia, she sent her father a handwritten letter that he still keeps in his wallet.

“I wish you could see how my heart has changed, how it is open to the world around me in a beautiful way,” she wrote. “I am happier and more content than ever.”

In Philadelphia, Ms. Payton moved with Mangal-arti and a few other devotees into a temple, and then into a rented house, while they worked to open the Mantra Lounge in the trendy neighborhood of Fishtown.

Mangal-arti was born in Calcutta. She found the Hare Krishna movement in her early 20s, while working in a bank in Australia, and she chose Devamrita Swami as her spiritual master, a role akin to a priest or mentor. She is charismatic and bright-eyed; in video recordings of her teaching, she speaks cheerfully and seems to make intense eye contact with her listeners.

Ms. Payton said in an interview that her mental health was already deteriorating badly by the time she got to Philadelphia. She had been raped in college, and was experiencing symptoms associated with post-traumatic stress disorder.

Mangal-arti was the first person Ms. Payton told about having been raped. Ms. Payton recalls her suggesting that her ensuing struggles were caused by insufficient faithfulness: She wasn’t bowing deeply enough during prayers, wasn’t working hard enough, and was trusting too much in her own instincts. Ms. Payton listened, and tried to purge herself of desire and disobedience. She began covering her head with her sari, as a sign of devotion.

In an initiation ceremony in 2017, she swore to abstain from “illicit sex,” intoxication, meat-eating and gambling, and she received a new name designating her as a servant of God: Gaura-bhakti.

The ceremony was standard for devotees seeking deeper commitment to the faith. What was not standard was that Ms. Payton felt that Mangal-arti was becoming the most important person in her life.

Three women who lived in the house said that they shared private information with Mangal-arti, only to discover that Mangal-arti later shared it with others. They said that Mangal-arti extended and then withheld affection in ways that were emotionally manipulative. Ms. Payton would later say that Mangal-arti fostered an “atmosphere of fear.”

Mr. Dasa, the spokesman for ISKCON, said the organization acted quickly to investigate Ms. Payton’s and other followers’ claims that Mangal-arti engaged in emotional abuse and manipulation.

“We in no way condone” Ms. Payton’s experience of “serious problems” at the ashram in Philadelphia, Mr. Dasa said in an interview. “It doesn’t at all represent the typical experience of a Krishna devotee at any of our hundreds of temples around the world.”

Mangal-arti did encourage Ms. Payton to pursue therapy independently, which her parents paid for.

“Mangal-arti appeared to be the only person whom Justine had a personal relationship with, intensifying her reliance on her,” her therapist wrote in a later statement summing up their sessions.

Ms. Payton stopped seeing that therapist after less than a year. Her last session was a joint meeting with the therapist and an “intense and overbearing” Mangal-arti, according to the therapist’s written account.

Other devotees reported similar experiences. After meeting Mangal-arti in Canada, Shannan Mann moved into the ashram in Philadelphia with Ms. Payton and a handful of others who worked at the Mantra Lounge. Mangal-arti had a long list of rules, down to how she should shower and how she should part her hair, Ms. Mann said. Ms. Mann, too, said Mangal-arti would be sweet and maternal one moment, and jealous and hostile the next. (In a statement, Mangal-arti called Ms. Mann’s account of her experiences “completely false and baseless”.)

Ms. Mann had known Ms. Payton in New Zealand. In Philadelphia, she was struck by how much Ms. Payton’s appearance had changed. She had lost weight and become strikingly pale, and she barely spoke. She had been transformed from a person Ms. Mann saw as bold and inquisitive to someone reduced to staring at Mangal-arti and “just wanting her approval for everything.”

In a statement, Mangal-arti disputed almost every element of Ms. Payton’s account of her time in Philadelphia, and said Ms. Payton seemed to have embarked on a “targeted campaign” against her. She also pointed out that Ms. Payton often thanked her during this period for her support.

Some people at the small ashram were happy. Mangal-arti provided multiple testimonials to The Times from people who spent time at the ashram in Philadelphia or who said they had known Ms. Payton and Ms. Mann in the past. All of them appear to remain involved in ISKCON or its practices. They described Mangal-arti as generous and fair, and characterized Ms. Payton and Ms. Mann as behaving erratically at the time, and as spreading falsehoods afterward.

Ms. Payton had been in Philadelphia for five years when she got Covid and moved into the basement of the ashram. For three weeks, she was on her own, free from the grueling schedule of selling and cooking and cleaning that had felt increasingly oppressive to her. “Things are really wrong here,” she remembers thinking.

Lisa and Dean drove to Philadelphia after Christmas to retrieve their daughter, picking her up on the curb outside the ashram early in the morning. She had stuffed her belongings into a few black garbage bags. They barely spoke as they drove back to Illinois.

Over time, she came to see what had happened to her in Philadelphia as abusive.

In 2021 she and three other former and aspiring devotees registered formal complaints against Mangal-arti that were reviewed by ISKCON’s governing body, a board that oversees the global organization. Some of the four complainants, and others, also made complaints about Devamrita Swami’s leadership.

After two years, the board’s North American branch ruled last year that Mangal-arti must apologize in writing to Ms. Payton and the other Mantra Lounge community members whom she had “hurt (mistreated, abused, shamed)” by her “actions and words,” and that she must not lead any ISKCON event or organization for three years, among other consequences.

In her statement, Mangal-arti described the ruling as hastily completed only after the The Times contacted ISKCON leadership last year, an accusation Mr. Dasa strongly denied. She said the organization did not follow up on the evidence she submitted to defend herself, and that ISKCON had issued an adjudication without an investigation.

ISKCON’s committee overseeing gurus reached a decision in early May requiring Devamrita Swami to undergo education on trauma and to submit a written plan to ensure that the “unhealthy dynamics” of Mantra Lounge would not be repeated, among other things. Mr. Dasa said the organization was also considering new training protocols “for ISKCON leaders to avoid these problems.”

The Mantra Lounge in Philadelphia closed in 2021.

Ms. Payton has tried to start her own life over, enrolling in graduate school in North Carolina, writing about her experiences, and restoring her relationships with her parents. Her boyfriend of two years recently proposed to her in a rented geodesic dome in the mountains near their home.

But it would be too simple, in her view, to call hers a happy ending. She lost friends permanently, she remains deeply ashamed, and she struggles with a sense that she has lost time she will never get back.

She still finds beauty in certain religious texts, including the Bhagavad Gita — although not the translations by the Hare Krishna movement’s founder. But she no longer practices any religion, and said she cannot imagine associating with a religious institution again.

She tries to be open to the experience of wonder, she said. “I think that’s at the root of what I was seeking all along.”

Susan C. Beachy, Alain Delaquérière and Sheelagh McNeill contributed research.