When Anita Pallenberg made the first move on Keith Richards, she had already been romantically involved with his bandmate, Brian Jones. But the "sixth Rolling Stone," who made the rockers look like "awkward adolescents," had a lasting effect on the band.

The German-Italian actress, who died in 2017 at age 75, is the subject of a new book, "Parachute Women." It explores the four muses, including Pallenberg, who helped transform the group into international rock stars during the ‘60s and ‘70s. Author Elizabeth Winder told Fox News Digital she tracked down several sources who were "very, very close" to the personalities featured in her book.

"This is such a wild, fascinating and compelling story," said Winder. "It’s got so much drama … and no one has written a book like this, so I thought I’ll do it myself."

"These were all women who were not only fascinating but also made up their own rules," she said. "That’s what I found so intriguing about them."

Book cover of Parachute Women

Anita Pallenberg is one of the muses for the Rolling Stones featured in Elizabeth Winder's new book, "Parachute Women." (Hachette Books)

Pallenberg was a fashion model in her 20s when she attended her first Rolling Stones concert in 1965 with a friend in Munich, the New York Times reported. According to the outlet, she managed to go backstage and offered Jones some marijuana and hashish before they headed to his hotel room. The pair quickly became a couple.

"She boosted his confidence," Winder said. "He was really losing his ground within the power dynamics of the Stones. Having a woman like Anita on his arm changed everything. She was beautiful, but she offered so much more than that. She had a powerful presence."

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A group portrait of the rolling stones in 1964

This photo of the Rolling Stones, circa 1964, shows Mick Jagger, left, Keith Richards, Brian Jones (back), Bill Wyman and Charlie Watts. (Stanley Bielecki / ASP / Getty Images)

"At the show where they met, Brian and Mick had just gotten into a really big fight," Winder said. "Mick had been screaming at Brian. Brian was in tears because, on a certain level, he was also very sensitive when it came to himself and his issues. When he met Anita, he was in an incredibly vulnerable state. According to accounts, he spent the whole night crying in her arms and talking about his problems. And within a matter of days, he emerges with Anita and has this incredible confidence that Mick hadn’t seen in years. That’s when Mick realizes, immediately, that it had something to do with this new girlfriend."

Anita Pallenberg wearing a white and black dress

Anita Pallenberg was a model and actress who captivated the hearts of three members of the Rolling Stones. (Andrew Maclear / Getty Images)

In his 2010 memoir, "Life," Richards admitted he was "fascinated by her from what I thought was a safe distance."

"I thought certainly that Brian had got very lucky," he wrote. "I could never figure out how he got his hands on her. … The truth was I’m looking at Anita, and I’m looking at Brian, and I’m looking at her, and I’m thinking, ‘There’s nothing I can do about this. I’m going to have to be with her. I’m going to have her, or she’s going to have me. One way or another.’"

But the Jones and Pallenberg's relationship was tumultuous.

Anita Pallenberg smiling wearing a furry coat and white turtle neck dress posing next to Brian Jones who is also warmly dressed

Anita Pallenberg had a tumultuous relationship with lead guitarist Brian Jones. (J Wilds / Getty Images)

"I would hear the thumping some nights, and Brian would come out with a black eye," Richards wrote. "Brian was a woman beater. But the one woman in the world you did not want to try and beat up on was Anita Pallenberg. Every time they had a fight, Brian would come out bandaged and bruised."

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Anita Pallenberg and Keith Richards wearing white blouses and striped pants sitting in bed

Keith Richards and Anita Pallenberg are shown circa 1969. (McCarthy / Daily Express / Hulton Archive / Getty Images)

According to the New York Times, Pallenberg’s relationship with Richards began after he rescued her from being beaten by Jones in Morocco in 1967.

"I think that had a massive impact on the band," said Winder. "Brian Jones was physically abusive to Anita, and this continued for a little while. And then in Morocco … she finally had enough. She and Keith had been, I think, interested in each other from afar for a while. And she ran off with Keith. … But by that point, Brian was already lost in the heavy drugs he had been taking for some time. It’s hard to say what would have happened to Brian Jones if Anita hadn’t left him. I think he still might have met that same sad fate. … But Anita and Keith became this force of nature."

Anita Pallenberg wearing a peacoat and a feathered hat in the arms of Keith Richards

Keith Richards and Anita Pallenberg quickly became inseparable. (Michael Webb / Getty Images)

In 1969, Jones drowned in a swimming pool. He was 27. He was fired from the Rolling Stones about two to three weeks before his death, Richards wrote. Some reports claimed it was Jones who left the group over creative differences and his increasing drug habit.

A close-up of Brian Jones playing the guitar

Brian Jones died in 1969. He was 27. (Michael Ochs Archives / Getty Images)

"I’ve heard from several sources that, on the surface, Anita was kind of dismissive immediately following Brian’s death," said Winder. "She acted like she didn’t care. But underneath, she cared quite a bit. She felt some sadness and perhaps even some guilt. She would stay up at night and obsessively look through old newspapers and clip-out pictures of Brian Jones. She would put them in notebooks. She began this archive of pictures of Brian that she would talk about to a few different people late at night. It seemed that it did affect her. And it seemed, for obvious reasons, that this was probably something she and Keith did not discuss … I know [Brian’s death] was something the band dealt with privately."

It's been rumored that Pallenberg had an affair with frontman Mick Jagger after they appeared together in the 1970 film "Performance." However, the New York Times noted that she always denied the claim and instead credited their on-screen chemistry to "method acting."

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Anita Pallenberg applying lipstick onto Mick Jagger

Anita Pallenberg and Mick Jagger starred in the 1970 film "Performance." (Andrew Maclear / Hulton Archive / Getty Images)

"Anita was not your typical rocker girlfriend," said Winder. "She never took a back seat. She was never hanging out in the back or waiting for the guy to tell her what to do. Anita always did her own thing. She was always out in front. And people followed her. People gravitated towards her. That was so unusual for a woman back then, especially a woman dating a rock star. When you see photos of Anita and Brian or Anita and Keith, it never looks like Anita is on the guy’s arm. It looks like the guy’s on Anita’s arm."

Anita Pallenberg walking ahead of Keith Richards wearing a hat that covers her face

Keith Richards and Anita Pallenberg are seen arriving at London's Marlborough Street Court in 1973. They were charged with possession of cannabis. Richards was also charged with firearms offenses. (Frank Barrett / Keystone / Hulton Archive / Getty Images)

"Mick realized that Anita was someone they needed," she continued. "It’s well-documented that he valued her opinion in so many ways. She was not a musician at all, and yet he came to her whenever he needed an opinion about a song. And this lasted for years. He saw her as very valuable. To be frank, he did want her for himself. It wasn’t just that he wanted to sleep with Anita because she was an attractive woman. It was much bigger for him."

According to Winder’s book, Richards begged Pallenberg to turn down the role in the racy film "Performance." He reportedly even offered to match what she was being offered financially just so she could end her involvement with the movie. However, Pallenberg went on to do the film. Richards reportedly "sulked at a distance" as Pallenberg shared steamy scenes opposite Jagger. He refused to confront Jagger out of fear it would affect the band.

Keith Richards in an animal-print coat smoking a cigarette next to Anita Pallenberg

In his memoir, Keith Richards described how both he and Anita Pallenberg struggled with addiction, which contributed to the breakdown of their relationship. (Graham Wiltshire / Hulton Archive / Getty Images)

"He blunted the pain, as he would for the next decade, with heroin and coke, writing love notes in the rain," Winder wrote.

During the ‘70s, Pallenberg and Richards were inseparable. They were together for 12 years but never married. The couple shared three children. Their second son died of sudden infant death syndrome in 1976.

"What caused their relationship to end … was the issue with drugs," Winder said. "They both started using heroin in the late ‘60s. By the ‘70s, they were both struggling with heroin addiction and going in and out of sobriety. And Keith, by the late ‘70s, realized that he had to stop. He had to stop using heroin completely. And Anita, according to him, seemed unwilling or unable to stop."

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Anita Pallenberg smiling holding her son next to Keith Richards wearing sunglasses

Anita Pallenberg and Keith Richards were together from 1967 to 1980. (John Minihan / Getty Images)

"But there was also the issue of infidelity," she continued. "This was something much more complicated than drugs. And there was something else that hasn’t been written about as much. As the Stones got really big, Anita’s relationship with Keith began to suffer. As a woman, she began to feel more pushed to the side and marginalized."

Pallenberg's career was overshadowed by the Rolling Stones as they continued skyrocketing to fame.

Keith Richards wearing a black jacket, white shirt, scarf and a fedora hat with sunglasses while holding a pen

Keith Richards previously detailed his relationship with Anita Pallenberg in a memoir titled "Life." (Rune Hellestad / Corbis via Getty Images)

Richards wrote that he loved Pallenberg but that she was "unstoppably self-destructive." He realized they were "spinning out of control" as he tried to get clean.

"I would have stayed with Anita probably forever, but when it came to that very important time when dope was out of the picture from now on, she didn’t stop," he wrote. "She’d never stopped, in fact. When we did it for several months in 1977, she’d be sneaking stuff around the back. I knew that she was on it; you can just tell by the eyeballs."

Keith Richards lighting Anita Pallenbergs cigarette

Anita Pallenberg inspired Keith Richards' personal style throughout their relationship. (Archivio Cameraphoto Epoche / Getty Images)

According to the Los Angeles Times, Pallenberg had an affair with Scott Cantrell in 1979. The 17-year-old was a groundskeeper at the home she and Richards shared. While in her bed, Cantrell shot himself with a gun owned by Richards, the outlet reported. At the time, the star was overseas recording with the Stones.

Richards became involved with Swedish model Lil Wergilis, who also went by Lil Wenglass or Lil Green. In his memoir, Richards compared his "beautiful lover" to Marilyn Monroe thanks to her "dazzling" features and blonde mane.

Pallenberg and Richards split in 1980. In 1983, Richards married his current wife, American model Patti Hansen. They share two daughters.

In 1987, Pallenberg's sister got her famous sibling in rehab, The Guardian reported. In 1994, Pallenberg earned a fashion degree at London’s Central Saint Martins College. She also returned to films.

When Pallenberg died, Richards released a statement that read, "A most remarkable woman. Always in my heart."

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Mick Jagger, Anita Pallenberg and Keith Richards wearing coats and walking together

Mick Jagger, left, Anita Pallenberg and Keith Richards are seen at a London airport. (Central Press / Getty Images)

Pallenberg is credited for influencing the Stones’ look, introducing them to dangerously low-rise pants, furs and feathers. In her lifetime, she made her mark with films like "Barbarella," "Candy" and "Le Berceau de Cristal." Her personal style continues to be referenced by designers.

Anita Pallenberg wearing a golden dress and holding a walking stick

Anita Pallenberg is shown walking the runway at the Pam Hogg show at Fashion Scout during London Fashion Week Spring/Summer collections on Sept. 16, 2016. (Eamonn M. McCormack / Getty Images)

"Keith learned from Anita in a very direct way," Winder said. "… When he was with Anita, he adopted so much of who she was. He would put on a pair of Anita’s pants that she had thrown on the floor the night before. … He also picked up on her rebelliousness, her self-possession, her playful ways of flirting with darkness. … And there was no turning back."

The Associated Press contributed to this report.