It’s no secret that King Charles and Princess Diana’s seemingly fairytale romance turned out to be a nightmare, but according to one author, things were much darker behind closed doors.

“The King: The Life of Charles III,” by Christopher Andersen, is a new book about Queen Elizabeth II’s eldest son. He spoke with a number of palace insiders as well as people who have known or worked closely with the former Prince of Wales over the years. His mission was to delve deeper into the 74-year-“lonely” old’s childhood and military training, as well as several scandals involving his relationships that rocked the House of Windsor.

According to Andersen, the marriage of Charles and Diana became so volatile that royal protection officers were wary of all the weapons strewn about the palace.

“He has a terrible temper,” Andersen said of the king. “I mean, it’s a fantastic temper. Tantrums on a regular basis, as well as throwing a bootjack [at her]. It’s a heavy wooden device made of iron and wood for putting on hunting boots. He hurled it at Diana’s head, just missing her.”

According to Andersen, Charles’s former valet Ken Stronach was in the room “when Charles, in the middle of an argument with Diana, grabbed a heavy wooden bootjack and threw it at her, missing the princess’s head by inches,” as quoted in the book.

“But there are guns everywhere in that palace,” Anderson claimed. “They enjoy having shooting parties. So, there are shotguns and handguns for security, as well as rifles [for] security forces… they were concerned about the violence. There was a lot of screaming and shouting, as well as slammed doors. Don’t forget Diana, who threw herself down the stairs when she was three months pregnant with [Prince] William and landed at the feet of the queen and Princess Margaret. As a result, there were numerous violent incidents. It could have been a lot worse. And [security] was concerned that not only would someone commit suicide or cause harm, but that we might be talking about murder. As a result, they attempted to keep the weapons away from the royals.”

During the marriage, Charles “had sunk into a deep depression” and thought he was “on the verge of a nervous breakdown,” according to Andersen. He allegedly told one of his confidants, Arnold Goodman, “I have nothing to live for.” According to Goodman, Charles was “showing the classic signs of depression.” Not only did Charles believe he was trapped in a loveless marriage, but he also worried that a divorce, if granted by the queen, would have “grave repercussions for his children, the royal family, and the monarchy itself.”

Goodman, according to Andersen, expressed his concerns to royal protection officers. Diana’s former bodyguard, Ken Wharfe, described the atmosphere as “highly combustible.” One bodyguard told Andersen that the clashes between Charles and Diana were “so raw” that “violence seemed inevitable.”

“The sheer firepower contained within Highgrove’s walls posed a special problem,” Andersen wrote. “Guns were strewn about the premises -‘shotguns, rifles, pistols, the whole lot,’ and the detectives in charge of protecting members of the royal family were deeply concerned that any of these could be used to commit suicide, homicide, or both in the ‘heat of anger.’ There was also legitimate concern that William and Harry would be used as human shields. To be safe, all firearms were kept under lock and key.”

Diana and Charles’ problems began long before their so-called fairy-tale wedding. The heir to the British throne, Charles, was allegedly pressured to end his relationship with then-Lady Diana Spencer or propose. Diana had reservations about walking down the aisle before the wedding, especially after discovering a bracelet Charles had made for Camilla, his former flame. The marriage deteriorated, and the unhappy couple engaged in extramarital affairs.

Andrew Morton published “Diana: Her True Story” in 1992, a shocking account of the marriage’s demise. It also discussed Charles’ relationship with Camilla and Diana’s mental health issues. It was not confirmed at the time that the princess had secretly collaborated with the British author on the book. The couple announced their divorce the following year.

In 1996, the divorce was finalized. Diana died a year later, at the age of 36, from injuries sustained in a car accident in Paris.