In May 2013, Huma Abedin and Anthony Weiner allowed filmmakers full access to his mayoral campaign with the hopes that the end result would document a spectacular political comeback, with Weiner being sworn in as mayor of New York having emerged from a scandal centered on explicit texting that forced him to resign from Congress.

Things did not go quite according to plan.

Instead, “Weiner,” a new documentary that The New York Times was allowed to view exclusively ahead of its premiere at the Sundance Film Festival on Sunday, provides an unfettered look at the implosion of Weiner’s mayoral campaign and a wrenching inside account of the couple’s interactions in the aftermath of his second explicit texting scandal.

The film overflows with juicy moments about Weiner. As the second scandal unfolds in July 2013, Weiner is shown panicking; misleading the news media; and, at one point, racing through the back halls of a McDonald’s to avoid a woman with whom he traded inappropriate texts, whom his campaign code-named “Pineapple.”

But the footage also centers on Abedin, who is best known as the closest aide to Hillary Clinton, another woman who has endured public humiliation and political scandal.

Just after the news broke that Weiner had exchanged lewd messages with women online using the pseudonym Carlos Danger, Abedin maintained a steely calm.

When a young campaign staff member, on the verge of tears after the revelations and ensuing media harassment, prepared to leave the couple’s Park Avenue apartment, Abedin offered some advice. “Just a quick optics thing?” she said to the woman. “I assume those photographers are still outside. So, you will look happy?” The staff member agreed.

The film comes at an uncomfortable time for Hillary Clinton’s presidential campaign, as it grapples with attacks from both the Republican candidate Donald Trump and others reminding voters of the more sordid sexual episodes of her husband’s past. In recent weeks, former President Bill Clinton’s behavior has been raised in the Republican presidential primary by Trump, who questioned his “terrible record of women abuse,” and also during the Democratic debate on Sunday, when Sen. Bernie Sanders of Vermont, Hillary Clinton’s chief rival for the nomination, called the former president’s behavior “deplorable,” in response to a question about Bill Clinton’s scandals.

Hillary Clinton does not appear in the film (aside from in news footage), but her presence is frequently felt as Abedin — with facial expressions ranging from hurt to hostile — copes with the second sex scandal to engulf her husband’s career and crush her hopes of becoming a powerful political wife.

Abedin is portrayed from the film’s opening minutes as the linchpin to Weiner’s attempted comeback after his resignation from Congress. “Did Huma want you to go back into politics?” one of the filmmakers asks Weiner. He does not hesitate. “She did,” he says. “She was very eager to get her life back that I had taken from her.”

Even in scenes in which Abedin is not shown, the focus is almost always on her: How was she able to forgive Weiner the first time, the film repeatedly asks, and would she ever be able to forgive a second transgression?

Abedin, who has worked for Hillary Clinton since she was a 19-year-old college student and is so close to the former first lady that she is often referred to as a surrogate daughter, has lately become a source of intense controversy.

Republican lawmakers have questioned Abedin’s arrangement to accept outside income as a consultant while working for Clinton at the State Department. Conservative groups have filed lawsuits to press the State Department to make Abedin’s emails and employment records public. And Republicans have seized on an inquiry by the State Department into whether she was overpaid nearly $10,000 by the government while on maternity leave in 2012. (Democrats say Abedin has been used as a political pawn in efforts to damage Clinton.)

But none of those controversies are as deeply personal or as potentially distracting to Clinton’s presidential campaign as the visceral film. “Weiner,” which will be released in theaters on May 20 by Sundance Selects, a distributor that has previously handled Oscar-nominated films, is expected to have its television premiere on Showtime in October, just weeks before the general election.

Trump has already sought to portray Clinton as an enabler of her husband’s sexual behavior and has tried to connect Weiner’s online behavior to a larger stew of Clinton sex scandals.

“Weiner” has become a source of heightened anxiety for Abedin and the Clinton campaign. She and her husband have repeatedly pleaded with filmmakers to see the movie, but have not been allowed to do so, according to people with direct knowledge of the conversations who could discuss the sensitivities around the film only without attribution, as the project has been kept under tight control. A spokesman for the filmmakers denied this and said they would have shown the couple the film had they asked.

Abedin and a spokesman for the Clinton campaign declined to comment.

With less than two weeks until the Iowa caucuses on Feb. 1, the Clinton campaign has already had to deal with the impact of another film release, “13 Hours,” the Michael Bay-directed movie about the 2012 attack on a U.S. diplomatic compound in Benghazi, Libya. Trump rented out a theater in Des Moines to offer free screenings of the movie.

“Weiner,” a 90-minute independently produced film, was directed by Josh Kriegman, who served as the chief of staff for Weiner’s district office from 2005-06, and Elyse Steinberg, known for the PBS documentary “The Trial of Saddam Hussein.” “Weiner” relies heavily on humor, incorporating extensive footage of late-night comedians mocking him, and has a 1970s glam-rock, funk and reggae soundtrack.

The directors of “Weiner” declined to be interviewed for this article, but a producer of the film, Julie Goldman, said that Abedin’s role as filming began “was not clear at all.” She added, “Things, of course, changed quite drastically.”

Why did Weiner and Abedin continue to allow access after the scandal broke?

“We don’t know,” Goldman said. “I think they were very comfortable with Josh. It was also unfolding so rapidly.”

Hillary Clinton is referred to in overt and subtle ways throughout “Weiner.” One sequence focuses on a claim in New York magazine that Abedin was being pressured to choose between remaining a Clinton insider and supporting her husband.

Abedin turns to Hillary Clinton’s longtime spokesman, Philippe I. Reines, for guidance, preferring his counsel to Weiner’s terse advice toward the end of his campaign that she “act like a normal campaign candidate’s wife” and say, “I think Anthony is doing an amazing job.” Abedin is also shown heeding the suggestion of Reines to not appear in public with Weiner as he casts his ballot.

CNN, which in 2013 abandoned a disputed documentary project about Hillary Clinton’s career, placed an unsuccessful bid on the film.

“Weiner” includes moments between Weiner and Abedin that Goldman called “very normal and engaging.” In one snippet early on, when the couple are alone in an elevator, Abedin looks Weiner up and down and says, with a hint of disgust, “I’m not crazy about those pants.”

The contrast between Abedin’s public and private faces can be striking. One scene has the couple in a small office working the phones for campaign contributions. Abedin uses a sweet voice when she is asking for money. “How was the engagement?” she says on one call. “I want all the details!”

The film then cuts to her hanging up, showing a total change in demeanor. “His wife is going to max out, and he’ll try to raise another five,” she says flatly.

Weiner says in the film, at the very end: “I don’t regret letting you follow me around. I wanted to be viewed as the full person I was.”

Abedin never says whether she regrets the decision.