PARK CITY, Utah — The Sundance Film Festival was rocked Friday by an explosive documentary detailing nearly a decade of Michael Jackson’s alleged sexual abuse against two boys, who were just 5 and 10 years old, respectively, when they first met the late singer.

Called “Leaving Neverland,” the film has been slammed by the Jackson estate, which said it was “yet another lurid production in an outrageous and pathetic attempt to exploit and cash in on Michael Jackson.” A fan of the King of Pop was stationed outside the Egyptian Theatre in Park City, passing out “Project Michael” flyers giving “another perspective.”

In the lead-up to the film’s premiere, the festival took extraordinary precautions, stationing at least seven police officers on the theater’s premises after threats of violence. Sundance also hired state health-care workers to tend to audience members who might become triggered by the disturbing material. Indeed, many viewers got up from their seats and walked out during explicit descriptions of the abuse.

The four-hour documentary runs down, in vulgar terms, Jackson’s alleged relationships with the two accusers — Wade Robson and James Safechuck — which began around 1986.

Jackson died of an overdose of prescription drugs in 2009.

“He helped me with my career,” said Robson, who went on to become a choreographer for N’SYNC and Britney Spears. “He also sexually abused me for seven years.”

Robson was born and raised in Brisbane, Australia, and became obsessed with Jackson after his mother brought home the music video for “Thriller.” The 5-year-old perfectly mimicked the moves, and went onto win a local dance competition in 1987 that gave him the opportunity to meet Jackson while he was there on tour.

Later, on a trip to Disneyland with his family, Robson would meet Jackson again, when the singer invited the boy and his family to Neverland Ranch, his 2,700-acre estate. There, Robson claims he and his sister played on the grounds — which included a zoo, carnival and movie theater — and Jackson asked the family to stay the weekend after meeting them just four hours prior.

“The trippy part is we felt like we knew him,” Robson says. He was thrilled when Jackson invited him and his sister, who was 10, to sleep in his bedroom that evening. The night before Robson and his family were due to depart for the Grand Canyon, the boy woke up to Jackson sobbing on the floor in the dark.

“I’m just so sad you are going to leave,” the singer said. Jackson convinced Robson’s mother Joy to let him stay five more days while the rest of the family visited Arizona. She agreed, and that lapse of judgement, allowing a 7-year-old boy to spend a week with a man he barely knew, allowed Jackson’s alleged sexual abuse to begin.

Robson claims the lewd acts started with mutual fondling, then evolved to kissing, showering together, masturbation, nipple squeezing and oral sex. He said Jackson told him, “You and I were brought together by God. This is how we show our love.”

Jackson also sought to put a wedge between Robson and his parents, calling him “son” and telling him, “Don’t trust women.”

“Once the abuse started that first week, every night I was with him there was abuse, with my mother in the next room,” Robson said.

Safechuck was a California child actor, who in 1987 starred in a Pepsi commercial featuring the King of Pop. Jackson took a liking to him, and called up the boy’s home, asking his mother, Stephanie, if he could send a film crew to interview Safechuck. She enthusiastically agreed, and the kid was filmed talking about himself, lying in his bed, and then dancing.

“Now that I look back at it,” Safechuck said, “it was almost like an audition for him.”

Jackson started spending time at Safechuck’s home, often spending the night. Stephanie would even wash the wealthy singer’s clothes. Jackson invited the family to join him on a trip to a Pepsi convention in Hawaii, and he wanted 10-year-old Safechuck to sleep in his room.

“I didn’t think it was appropriate for my son to go sleep with him,” Stephanie said. “And that’s how it was the first trip.”

In an audio recording heard in the documentary, Safechuck asks Jackson, “What was the best thing about Hawaii?” Creepily, he responds, “Being with you.” And at just 10 years old, he spent his entire summer with Jackson, who introduced him to celebrities such as Tina Turner and Harrison Ford, and lavished him and his family with presents and vacations.

“In Paris, he introduced me to masturbation,” Safechuck said. “And that’s how it all started.”

As their relationship intensified, Jackson made the boy run drills to get his clothes on quickly and quietly if he heard somebody coming. He said Jackson warned him, “If people find out, his life would be over and my life would be over.”

Safechuck says that he was the first visitor to the Neverland Ranch, and claims to have had sexual relations with Jackson in its game room, third floor attic, movie theater, pool, jacuzzi and train station. “It happened every day,” he said.

Both Safechuck and Robson say they were in love with Jackson, an affection that crippled them into adulthood. In one particularly sick act, Safechuck claims the singer staged a mock wedding ceremony between the two of them, complete with written vows and a golden ring with a row of diamonds.

Back in Australia, Robson would have daily six- to seven-hour phone calls with Jackson. Smitten, Jackson gave the boy a nickname, “Little One,” and scrawled it on the many faxes he’d regularly send him. He soon convinced Robson’s mother to move her son and daughter to the US, abandoning her older son Shane and her husband, who suffered from bipolar disorder. Caught up in the allure of fame, she agreed.

But upon arrival, they were surprised to find that Jackson had put them up in a shoddy apartment the family had to pay for. Gone were the private cars, shopping sprees and Robson lost his promised role in Jackson’s “Black and White” music video. He soon discovered why: Macaulay Culkin.

The “Home Alone” actor has always denied being abused by Jackson, but he nonetheless was the object of his affection, spending much time at Neverland Ranch. Though the sexual acts sporadically continued for Robson and Safechuck, they claim Jackson replaced them with new, younger children.

By September 1992, “[Another] boy would sleep in Michael’s room and I would sleep on the sofa,” Safechuck says.

Adds Stephanie: “Every 12 months there was a new boy in his life.”

There were also women. Jackson wed Lisa Marie Presley in 1994, and divorced her in 1996, the same year he got married to Debbie Rowe.

“I remember Michael saying to me he’s going to have these public relationships with women,” Safechuck says.

When Jordy Chandler accused Jackson of sexual abuse in 1993, Safechuck and Robson both took the stand and said they had never been abused by Jackson.

‘Once the abuse started that first week, every night I was with him there was abuse, with my mother in the next room’ - Wade Robson

Jackson’s estate noted this in a statement: “Wade Robson and James Safechuck have both testified under oath that Michael never did anything inappropriate toward them.”

During the Chandler trial, Jackson’s team coached Robson and Safechuck, the men claim, to say “no” to every single question. That case was settled out of court for millions of dollars.

The two men finally told their stories in 2015, with Robson coming clean on the “Today” show. Both are now married with young children, having suffered from depression, anxiety and panic attacks in the ensuing years. Robson said protecting his own son was a major factor in his decision.

As the credits rolled at “Leaving Neverland” Friday, Safechuck and Robson were announced as surprise guests by the director Dan Reed. The Sundance audience gave them a long standing ovation.