When Joan Collins arrived in Hollywood, she received an ominous warning from Marilyn Monroe.

The future "Dynasty" star was at a party at Gene Kelly’s house when she spotted "a nondescript blonde" by herself.

"I only met her once," Collins told Fox News Digital. "She was sitting at the bar at Gene Kelly’s house. Gene Kelly and a group of friends were talking animatedly about politics. She was looking lonely and lost."

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Gene Kelly and Marilyn Monroe holding mugs in mid conversation

Joan Collins met Marilyn Monroe, right, at a party at Gene Kelly's house. (Hulton Archive/Getty Images)

The actress recalled the encounter and many others from her decadeslong career in a new memoir, "Behind the Shoulder Pads: Tales I Tell My Friends."

"I also felt lonely and lost," Collins shared. "I had just come to Hollywood. I was 20 years old and feeling a bit out of it. So I went and spoke to her. She was very sweet, gentle, kind."

In the book, Collins described how she had just signed under contract with 20th Century-Fox and already had her first starring role. It was the same movie that Monroe was originally supposed to star in.

Joan Collins being embraced by an actor in a film scene

Joan Collins starred in 1955's "The Girl In The Red Velvet Swing," a film that was originally considered for Marilyn Monroe. (20th Century Fox/De Carvalho Collection/Getty Images)

"They wanted me to play the lead in ‘The Girl in the Red Velvet Swing,’ but I’m too old," Monroe told Collins about the 1955 film.

According to the now 90-year-old, the mood lightened as they chatted "just like girlfriends" and savored "a couple of martinis." That was when Collins said Monroe "poured out a cautionary tale."

"She gave me some good advice," said Collins. "She said, ‘Watch out for the wolves in Hollywood, honey.’ I told her, ‘Well, I’ve been an actress for three years already doing British films, and we have wolves there, too.’ My father gave me good advice on how to deal with them."

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Marilyn Monroe leaning on her hands and smiling

Joan Collins said Marilyn Monroe, pictured here, warned her about "the wolves of Hollywood." (Baron/Hulton Archive/Getty Images)

However, the "extremely friendly" Monroe was adamant about telling Collins to be careful. After Collins told her, "All of us had to put up with having our bottoms patted and men leering down our cleavage" in the British film industry, Monroe replied, "That’s nothing compared to the studio power bosses."

Joan Collins wearing a black and white suit with a matching hat

Joan Collins went on to star in "Dynasty." (ABC Photo Archives/Disney General Entertainment Content via Getty Images)

"If they don’t get what they want, they’ll drop your contact," Monroe told her, as quoted in the book. "It’s happened to lots of gals."

It was a few days later when Collins alleged that a producer "pounced on me, trapping me against a wall" at the studio.

Joan Collins in a white evening dress

Joan Collins was faced with the casting couch when she arrived in Hollywood. (Silver Screen Collection/Getty Images)

"Breathing cigar fumes, he hissed, ‘You haven’t had anyone until you’ve had me, honey. I’m the biggest and the best and I can go all night,’" Collins claimed in the book.

Collins said she managed to free herself and rush back to the set. 

In the book, Collins wrote her first encounter with the casting couch was when she was testing for a role in 1952’s "I Believe in You." She alleged one of the producers made such obvious advances that she hid in a wardrobe in the costume department. With the help of "sympathetic dressers," she waited until he left the studio so she could go home.

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Joan Collins looking serious in a film still away from an actor

Joan Collins and Harry Fowler starred in 1952's "I Believe in You." (Hulton Archive/Getty Images)

Still, he persisted, Collins claimed. After her third test, the unnamed producer offered her a ride home "in his flashy Bentley." During the ride, Collins claimed he "grabbed my hand and put it on his open fly."

"I screamed in horror and yanked his hand away," Collins wrote. ‘What’s the matter? Don’t you want the part?’ he leered. ‘Not that much,’ I cried, childishly bursting into tears as I realized I had blown my chances. I’d never seen a naked man before, let alone felt one. ‘Are you frigid?’ he hissed. It was the first time I had been called that by a man, but sadly not the last."

In the book, Collins wrote that the producer was overruled by both the director and the head of the studio. Despite his threats, she got the role.

Book cover for Joan Collins memoir "Behind the Shoulder Pads"

Joan Collins has written a new memoir, "Behind the Shoulder Pads." (Permuted Press)

"However, he still pursued me, and when I told him I wasn’t interested and was still a virgin he called me a ‘frigid little witch,’" Collins wrote.

The star noted that it was not just producers who were predatory. She described how, at age 22, she repeatedly said no to "a handsome, if short, famous actor I was working with." She claimed that one night after shooting, the actor followed her car and shouted, "You stupid cow – you’ll be washed up by the time you’re 23!"

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Joan Collins wearing a leaopard dress sitting on a white couch

Joan Collins told Fox News Digital she refused to let any man get in the way of her career. (Eddie Sanderson/Getty Images))

Collins also detailed how her agent secured her an interview with "a very famous producer" for a part she wanted in a film. When she went to the producer’s office, his secretary was just leaving and told Collins to find him in a back room.

"I entered a bedroom, and a voice called, ‘Come on in,’ from another door," Collins wrote. "I tentatively walked in and there he was, lying in the bath without as much as a bubble to cover his embarrassment, with which he was tinkering."

Warren Beatty in a tux embracing Joan Collins in a printed dress

Warren Beatty with his then-girlfriend Joan Collins. (Hulton Archive/Getty Images)

Collins said she shuddered and looked away as they spoke about the film. The producer persisted for Collins to join him in the bath when she told him that her boyfriend – newcomer Warren Beatty – was waiting for her.

"What are you doing wasting your time with unknown actors?" the annoyed producer told Collins, as quoted in the book. "I’m an important man, we can have some fun… You won’t get much further in this business, kid, if you’re going to behave like a high-handed b----!"

Collins claimed she also "dodged and dived two old men" who promised her 1963’s "Cleopatra" if she was "nice" to them. The film went on to star Elizabeth Taylor and Richard Burton.

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A close-up of Richard Burton looking serious in a suit

Richard Burton starred opposite Joan Collins in 1957's "Sea Wife." (Screen Archives/Getty Images)

While filming 1957’s "Sea Wife," Collins claimed that Burton, her co-star at the time, told her that he slept with all his leading ladies. Collins said she declined his offer and he "barely spoke to me for the rest of filming." A similar encounter allegedly occurred with George Peppard in the 1970 film "The Executioner."

"He didn’t speak to me for the rest of the movie, and since I had to do a couple of topless scenes with him, this was embarrassing, to say the least," Collins wrote.

Collins told Fox News Digital that she refused to let any man stop her from pursuing acting.

Joan Collins looking uncomfortable sitting next to an actor

George Peppard and Joan Collins starred in "The Executioner," circa 1970. (RDB/ullstein bild via Getty Images)

"I really enjoy acting," she said. "I wouldn’t let those kinds of men ever intimidate me or make me stop doing my life’s work, what people nowadays call a dream. Do you think because some guy chases you around the wardrobe department or pinches your bottom, you’re going to give up acting? No way."

Not every man Collins encountered in Hollywood was a predator. She recalled meeting James Dean, who offered to drive her home in his new Porsche.

"He was part of the crowd that I would hang out with at Gene Kelly’s house," Collins recalled to Fox News Digital. "There was a bunch of us. We were young and just hanging out. There was Marlon Brando, Paul Newman."

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A close-up of James Dean wearing a red jacket

Joan Collins met a "moody" James Dean at a Hollywood party. (Michael Ochs Archives/Getty Images)

"But [Dean] was kind of moody," Collins described the "Rebel Without a Cause" star. "He didn’t say much. He didn’t join in very much. But he loved to drive. And he drove excessively fast… He just went from zero to 60. Somebody said he’s going to kill himself one day if he continues to drive so fast. I don’t believe in driving too fast. Cars are weapons if they’re used in the wrong hands."

James Dean at a gas station with his silver Porsche 550 Spyder

James Dean at a gas station with his silver Porsche 550 Spyder he named Little Bastard, just hours before his fatal crash in 1955. (Getty Images)

Dean was killed in a car crash in 1955 at age 24. He was in his Porsche.

"Of course, I was very upset," said Collins. "I just never liked going in fast cars."