A new book detailing 43 new allegations of inappropriate behavior by President Trump—including 26 alleged instances of unwanted sexual conduct—is set to land on bookstands early next week.

Many of the allegations in the book, All the President’s Women: Donald Trump and the Making of a Predator, published by Hachette, have been leveled before. But at least one, from Trump’s deep past, has not been previously aired: that, in the ’80s, he frequented a Mafia-run VIP sex club in Times Square, and once demanded a threesome with a porn star and a young-looking female.

The allegation centers on interviews with one self-proclaimed eyewitness, a former mobster named John Tino. But neither of the two women supposedly involved in the incident could be located by the authors—which leaves the charge in the hands of a man whose criminal record includes convictions for larceny, fraud, and forgery. Even the authors admit their account is hardly airtight, while nonetheless defending their work. “There are many people who will label Tino a liar and say his claims are false. I came away feeling his allegations are believable,” one of the authors, Barry Levine, told The Daily Beast.

The White House did not respond to requests to comment for this article, but Trump in the past has strongly denied any allegations of sexual impropriety. “That book is trash, and those accusations from 20 years ago have been addressed many times,” White House press secretary Stephanie Grisham said in a statement to Business Insider about All the President’s Women.

Tino swears he remembers Trump as “the real estate guy” during his years as hired muscle for the sex den, which he says was run by a notorious crime boss. In the book, to be published Tuesday, Levine and co-author Monique El-Faizy write that the secret club was allegedly frequented by rich and powerful men, including Trump. “Most of the women who worked there were porn stars, though not all. Trump preferred a woman who primarily performed live sex shows with her husband, though she acted in the occasional adult film as well,” the authors state.

Tino says in All the President’s Women that Trump always “wore a tie and never drank alcohol.” Trump—who was married at the time to his first wife, Ivana—allegedly always asked for the same woman, whom Tino had nicknamed “Tri.”

In the fall of 1982, according to Tino, his boss called and asked to see him. “The real estate guy is coming,” the boss said, in Tino’s telling. “He wants Tri and he wants another girl… for a ménage à trois.’”

Tino said his role at the club was to watch the hidden cameras that monitored each room, to ensure none of the women were “roughed up” during their liaisons. He would then collect the tapes that were recorded in black-and-white.

The book claims that one night, a young-looking female showed up at the club. According to Tino, “Tri asked the girl how old she was. She said she was a teenager,” without elaborating whether or not she was above the legal age of consent. The book states that “the real estate guy” spent an hour in the room.

The book also contains allegations from a woman named Karen Johnson, who alleges that Trump forcibly grabbed her “in the pussy” at a New Year’s Eve party at Mar-a-Lago in the early 2000s and then kissed her against her will. That allegation echoes Trump’s comments on the now infamous Access Hollywood tape where he boasted to Billy Bush how, “when you’re a star, they let you do it. You can do anything. Grab them by the pussy.”

Porn star Alana Evans also claims in the book she knows of at least three former porn stars who say they were paid to have sex with Trump. (Evans first told The Daily Beast in the fall of 2016 that Trump propositioned her and Stormy Daniels for a threesome.)

The alleged Times Square episode was much more difficult to verify, the authors of the book admit. The infamous Mob boss referred to in All the President’s Women was murdered in 1986 and the book provides limited evidence of the so-called Times Square VIP sex club’s existence. The videotapes referred to in the book have never been found. Despite exhaustive efforts by private investigators and reporters over recent years, both “Tri” and the “teenager” have never been located.

Levine acknowledges that several journalists tried and failed to confirm Tino’s explosive claims during the 2016 election and, like him, tried unsuccessfully to find the porn star involved. “To this day we don’t know if the porn star involved in this alleged incident is still alive or whether she is dead,” Levine told The Daily Beast.

Levine acknowledged that Trump supporters may not accept certain sections of the book as true.

“In this polarized society you have, and we interviewed many women who support Trump and blame the women and the victim, a great portion of the country sides with Trump but when you look at the facts they support the allegation,” Levine said.

In a long authors’ note that accompanies the Times S quare allegations, Levine talks about his efforts to corroborate Tino’s story.

“Over the months, through dozens of calls only to find that most of the people who associated with Tino are dead—either from natural causes or victims of mob violence themselves—I was able to locate two individuals who confirmed [Tino’s] work at the secretive sex den. Both of these individuals specifically remembered him by his mob nickname, ‘Blue Eyes.’

“One of the individuals, who is in his late eighties, said of Tino: ‘I remember ‘Blue Eyes’ from the office. He worked for us. He would come by. [—] had him running a place in Times Square.’”

But, Levine added, “despite efforts made by me and two private investigators—along with other reporters I spoke to who worked the story—I was unable to find ‘Tri’ or confirm whether she was still alive.

“I also conducted interviews with people in the mob-associated porn business specific to the Times Square sex scene in the early 1980s—not one of them knew for a fact what happened to this woman.”

The claims in All the Presidents Women are sure to be controversial, not least of all because Trump has always steadfastly denied all allegations of sexual misconduct and called the women making them “liars.”

Tino, who has been diagnosed with terminal cancer, told the authors he doesn’t want to take what he allegedly witnessed that night between Trump, the porn star “Tri,” and the “teenager” to his grave.

“That’s why I’m telling you this now,” he says in the book. “He’s the president.”