Documentary Secrets of Playboy premieres in the US on January 24. Photo / Supplied

Warning: Content may be disturbing

He masqueraded as a champion of sexual freedom, but a new series is set to lift the lid on the "dark underbelly" of Hugh Hefner and his Playboy empire, one rife with drug use, sexual abuse and bestiality.

Secrets of Playboy, a 10-part documentary premiering on American television network A&E on January 24, delves into the hidden truths behind Playboy, the Daily Mail reports.

Interviews with insiders including Hefner's ex-girlfriends Sondra Theodore and Holly Madison – who in December said she was "haunted" by her years in the Playboy Mansion – and former "Bunny Mother" PJ Masten.

"It was cult-like. The women had been groomed and led to believe they were part of this family," former director of Playmate promotions, Miki Garcia, told the docuseries.

"[Hefner] really did believe he owned these women. We had Playmates that overdosed, that committed suicide."

Hefner, who died aged 91 in September 2017, was "like a vampire" who "sucked the life out of these girls for decades", Theodore, a former model and actor who dated him in the late 1970s and 80s, said.

The now-65-year-old gave a disturbing account of her time with the iconic Playboy publisher, who launched the magazine when he was just 27, in 1953.

Theodore said Hefner's sexual demands became such that "you couldn't satisfy him, he wanted more and more and more".

"The group sex was at least five nights a week. They had a protocol. He liked to direct and you didn't segue away from it because you could tell it irritated him," she explained, saying the sex "broke me like you'd break a horse".

She alleged that Hefner was a prolific drug user who sent her out to buy cocaine numerous times, and whose poodle became addicted to it and used to lick it off the floor.

Not all of the drugs were for him, though. According to Hefner's executive assistant during the late '70s and '80s, Lisa Loving Barrett, he also kept a stockpile of Quaaludes, the powerful sedative Bill Cosby's accusers allege he drugged them with.

In the Playboy Mansion, the drugs were known as "leg spreaders" and considered a "necessary evil" because they made women do anything.

Barrett, along with Hefner and other staff at the mansion, had a prescription for the drugs and would collect them, she alleged, to store in a drawer in Hefner's bedroom, ready to give to women who he brought there.

The drugs helped fuel the Hefner-orchestrated "Pig Nights" – a weekly Thursday event, according to Hefner's valet of three years, Stefan Tetenbaum, that saw pimps bring half a dozen sex workers each to the mansion.

A doctor would allegedly examine the "pigs" for any sexually-transmitted diseases or infections before they were permitted to have sex with the guests.

"Sometimes he had a special woman who would come up, she was called The Bleeder," Tetenbaum told the documentary.

"She would use a very large syringe and draw blood from these different friends and a girl would come and perform fellatio (oral sex) or give them a hand job."

One of the most sinister allegations made in the documentary is that Hefner's sexual interests sometimes verged on the bestial.

"I walked in once and he was [gestures with hand] to our dog," Theodore said.

"I said, 'What are you doing?' He said, 'Dogs have needs'. I said, 'Stop that!' I never let him be alone with our dog again."

Even more disturbing was an incident that occurred when Linda Lovelace, the 1970s porn star who found fame with the film Deep Throat, arrived at the Mansion.

Former "Bunny Mother" PJ Masten said that when Lovelace arrived, "she was drunk and drugged" and forced into an orgy with Hefner's male friends.

"All of a sudden out of nowhere, a German Shepherd shows up. They got her so messed up they made her give the German Shepherd oral sex," Masten alleged.

"You want to talk about depravity? This is despicable!"

Masten also claimed the celebrities and VIPs who frequented Hefner's Playboy clubs could get away with anything – with a "clean-up crew" hushing up embarrassing incidents without involving police.

One of the most horrifying incidents was one allegedly involving TV presenter Don Cornelius, who allegedly invited two of the club's workers, sisters aged around 20 and 21, back to his house.

"Don had been in the club many times, many people saw him so they didn't have any fear at the time. These two young girls got in his Rolls Royce and went to his house," Masten said.

"We didn't hear from them for three days, we couldn't figure out where they were. They were separated, one locked in one room, the other in another. They were tied and bound.

"The sister could hear her (other sister) screaming. There were wooden objects she was sodomised with and she could hear her other sister being brutalised. It was horrible."

One of the girls managed to get out and make a call to Masten but the incident was never reported to the police. Cornelius's privileges were never even suspended – and he was back at the club the following week, she said.

Holly Madison, a former Playboy bunny who dated Hefner for eight years, opened up further about his refusal to use protection during sex and how the lifestyle in the mansion led her to consider suicide.

But, she said, "I was afraid to leave. Something always lingering at the back of my mind since the very beginning [was] if I left, there was this mountain of revenge porn waiting to come out.

"When you'd go out with Hef he was taking all kinds of naked pictures of these women when we're wasted out of our minds and he would print off eight copies, for him and all the women and pass them around. It was just gross," she recalled.

Russell Miller, who wrote a book about Playboy in 1985, said the sordid acts "exemplify" Hefner's attitude towards women.

"This is the dark underbelly of Playboy," he said.