In March 2014, Steven Currence gave undercover agents a grand tour of the dungeon hidden inside his Montana home.

The subterranean hellhole contained a heavy wooden cross and a smattering of chairs. The walls were covered in whips, chains, and torture devices. Currence boasted of blacking out the windows to dash any hopes of escape.

Here was the sinister lair where the 65-year-old planned to lock his sex slaves. One kidnapped woman would sleep in the basement torture chamber, while the other would be chained to his bed—with a chain long enough to reach the bathroom.

Currence believed he would soon purchase the women from the agents, who posed as human traffickers. The creep previously told the agents that he wanted a “housekeeper with benefits” who would “take care of things, clean the house, take care of me,” court records reveal.

“These slaves will never leave,” Currence said. “I’m not looking for love, they’re just going to be in here and they are going to be serving.”

But Currence wouldn’t be the one doing the shackling. Instead, the feds cuffed him two months later when he traveled to Arizona to buy two women at what he believed was a slave auction.

In September of this year, Currence was sentenced to seven years in prison.

He was one of four men nabbed in an FBI sting operation targeting an extreme slice of the human trafficking underworld: people seeking sexual and domestic slaves.

Court papers paint a disturbing picture of the lengths all four fiends went to keep their would-be slaves hidden. They outfitted their homes with things like soundproof boxes, window coverings, and even a 500-pound therapeutic bed with chains.

One man hired a contractor to turn his BDSM “playroom” into a dungeon so secure visitors wouldn’t know someone was inside. Another ordered a “date rape” drug from China to knock his victim out as he transported her across state lines.

The FBI operation aimed to tap into the seedy underground of Americans seeking slaves for sexual gratification, said George Steuer, an FBI supervisory special agent in Phoenix. If agents posed as buyers it might create more victims, he said, so they opted to advertise a fake sex-slave auction in Arizona.

“We believe it’s more of an extreme subset—a very deviant and hopefully minority culture that finds it appealing to have a non-consenting human slave,” Steuer said, differentiating the targets from mainstream trafficking for commercial sex and forced labor.

The goal was to find any victims who might need to be rescued. “We didn’t find any victims,” he told The Daily Beast, “but the market is definitely there.”

The operation launched in June 2013 after the FBI was tipped off to collarme.com, a fraudulent website where U.S. citizens attempted to buy Asian sex slaves.

The agents, posing as a human trafficking ring, then sent emails to a number of people using the site, after obtaining their addresses through a search warrant. They posted an open Web advertisement in August 2013 for a mock slave auction, court records show.

“Domestic slave auction to be held,” the ad began. “Attendance is limited and details will be provided to selected buyers. Females available are of Asian, Hispanic, and Eastern European descent, between 18 and 26 …. Interest in areas outside of available product can be discussed.”

FBI agents pared the suspect list by reiterating that the women were kidnapped, non-consenting and that the sale would be illegal. Many people walked away, Steuer said.

“We had over 100 persons that expressed interest,” Steuer said. “That’s where we got concerned ... We found many people who said, ‘This is what I’m in for. This is not fantasy.’ These people are going another step to really execute this transaction. The four we ultimately arrested showed up.”

Currence was one of the 100 suspects to take the FBI’s bait. He responded in an email, saying, “Definitely interested. Have personal stone dungeon and many years experience as trainer/owner.”

When the undercover agent informed Currence that the women were being held against their will, and that it was illegal, Currence said he intended to buy a slave for “life, permanent, and it is total slave, not play,” according to court records.

In February 2014, he told agents he wanted to purchase two “lots” from their sham website. A month later, the covert cops traveled to Currence’s Billings, Montana, home to see the dungeon. But the basement prison wasn’t complete; Currence pointed out where he intended to install cages for his victims.

Currence also announced that he’d hide the women’s passports so they had “no ID, no passport, no money, no clothes, and no idea where they are,” court papers show.

He laid out his plans further in April 2014, telling agents he was installing bulletproof plastic on the inside of his bedroom window to stop the slaves from posting “help” signs.

His evil plot came to an end in May 2014, when he traveled to Phoenix for what he believed was a slave auction. He brought with him custom-made shackles, along with a quitclaim deed to sell his property.

To get funds to purchase his slaves, Currence had agreed to sell a residence in Roundup, Montana—where he’d previously lived with his now-deceased wife, Kathleen. A report in the Montana Standard revealed she died from a gunshot wound to her right temple, but that the death was not deemed suspicious at the time.

Currence sold the home for a reduced price of $13,073 in exchange for cash and the two slaves, which would cost him $5,000 apiece. He was arrested when he arrived at a Phoenix-area warehouse, where his victims were said to be waiting.

The Montana dungeon master pleaded guilty in Arizona federal court to one count of attempted sex trafficking as part of a plea deal with the U.S. District Attorney’s office.

At his September 10 sentencing, Currence said he was “mortified” at his behavior, the Arizona Republic reported.

“I know deep in my heart that I would never ever hold someone against their will or try to force someone to do something through threat or force,” he said, according to the newspaper.

The three other suspects had equally disturbing motives—and one of them has a sordid criminal history.

Charles Bunnell, 52, an Orange County, California, computer repair shop owner, was previously convicted for false imprisonment with violence. He once handcuffed a victim while trying to have sex with her and cut her palm and middle finger, court papers indicate.

Prosecutors also cited a 1989 arrest for rape, where Bunnell held a knife to the victim’s throat, tied her hands with pantyhose and forcibly raped her.

On two occasions, Bunnell attempted to buy slaves from overseas online, court records show.

In the FBI’s sting, Bunnell went as far as offering assistance to the undercover agents posing as traffickers, saying he could keep the slaves sedated through hypnosis and drugs.

Bunnell told an agent he’d been involved in the slave trade for 12 years and “nobody ever got out.” He described a “retraining facility” in Nevada that could hold 12 to 18 pieces of “property,” court records reveal.

He told agents that his slave “training” included putting the women on a table, inserting a speculum into their vagina and warning them that he inserted a device that would explode if they tried to escape.

The ex-con said he wanted to bring a slave to California and keep her tied, hooded and gagged all day in a soundproof box, until he could “use it” when he got home, according to court papers.

Agents later found Scopolamine, a pharmaceutical he bought from China and intended to use to sedate his victim, prosecutors charge.

Bunnell pleaded guilty under an agreement with the District Attorney’s office. He was sentenced to nine years in prison, but court records indicate he filed an appeal in his case.

Meanwhile, Edward Stevens, 68, of Mesa, Arizona, told agents he wanted a slave for both domestic servitude and sexual purposes. He said he was installing a dead-bolted door on his spare bedroom and bars over the windows “so it would be harder for [the slave] to get out if I wasn’t directly supervising them.”

He was arrested in December 2013 when he showed up with $4,000 in his jacket pocket, ready to purchase his victim. The same day, police executing a search warrant discovered his special security door, handcuffs, ropes, paddles, long knives, and a speculum, court records show.

Stevens pleaded guilty under a deal with prosecutors and was sentenced to seven years behind bars.

Another Arizona slave buyer, Edward Kandl of Tucson, had previously made a $5,000 wire transfer to the sham Malaysian website in an unsuccessful attempt to purchase a female sex slave, according to court documents.

The 60-year-old arrived at the FBI’s fake auction with $10,000. As he was being cuffed, a search at his home revealed a secure room with a heavy therapeutic bed, which had a chain inserted through the frame. The window of the room was blacked out, and a single piece of lingerie was hanging in the closet.

The search also revealed firearms—including an Uzi—along with a homemade and unregistered silencer, parts for a pipe bomb and seven improvised explosive devices.

Kandl, pleading guilty under a plea deal, was sentenced to five years in prison.

After his arrest, Kandl tried telling law enforcement that although he knew the women weren’t consenting, he wouldn’t have purchased anyone who refused to go with him.

“Kandl was asked why he didn’t call the police and Kandl replied that he should have but his curiosity was piqued,” one FBI memo found in court papers read. According to the document, Kandl planned to interview the women to see if they were willing to go home with them. He told investigators he wanted to explain he could provide them with a better life.

When asked what that meant, Kandl said he’d provide a room, food, and clothes. He also planned to introduce his slave to the BDSM lifestyle, which he’d been engaged in for three years, according to the FBI document.

Kandl said the whole thing was a “bad idea” and that he “shouldn’t have done it.” He told investigators that in his life, “I did everything right until this stupid thing.”