Imagine a mystery novel about a shadowy online drug market that customers can access only with anonymous encryption software. You probably wouldn’t believe it, especially if at the end of the story the drug dealers shut down the market and take off with $12 million in customers' bitcoins.

But that’s exactly what seems to have happened in real life as rumors swirl about the sudden disappearance of an illicit site called Evolution. Since debuting in January 2014, the drug cyber-bazaar grew to become the largest on the Deep Web, the vast unindexed section of the Internet where criminal sites have operated largely without obstruction. Unlike the Silk Road and other prominent drug-trafficking sites before it, Evolution doesn’t appear to have been shut down by law enforcement, but by its own founders.

Evolution, the Silk Road and sites that are still online operate largely like an illicit Amazon or eBay. Users buy or sell any number of goods they wouldn’t be able to find on legal markets: from marijuana and heroin to firearms and contract hackers. The sites are accessible with Tor, the browser plug-in that anonymizes a user’s online activity, and trade in bitcoin, a decentralized cryptocurrency that’s difficult to trace to its owner.

Evolution’s operators, known only by their screen names “Verto” and “Kimble,” used this business model to great effect. The site had more than 14,000 drug listings and 12,134 non-drug listings including lethal weapons, according to the most recent report from the Digital Citizens Alliance last year.

But after existing within the Deep Web for more than a year, Evolution suddenly ceased to exist on March 17. The $11.7 million-or-so in bitcoin that disappeared with it are proof that the site was much larger than the Silk Road, which, despite attracting scores of headlines, only yielded $3.6 million in bitcoin for FBI auditors in October 2013.

That Evolution’s founders stole their user’s bitcoins, which they held on deposit for future purchases, hasn’t been confirmed. But accusations have surfaced throughout social media and Reddit, where a user known only as NSWGreat, who described himself as an Evolution seller, asserted that a heist had gone down.

“I have admin access to see parts of the back end, the admins are preparing to exit scam with all the funds,” NSWGreat explained. “I am so sorry, but Verto and Kimble have f**ked us all. I have over $20,000 in escrow myself from sales. I’m sorry for everyone’s losses, I’m gutted and speechless. I feel so betrayed.”

The FBI doesn’t appear to be behind the site’s downfall. There’s no takedown notice adorning the front page, and no arrests were announced, as they were when the Silk Road and Silk Road 2.0 were shut down. The bureau didn’t immediately respond to a request for comment.

Alex Winter, the director of “Deep Web,” a coming documentary about the Silk Road, said it shouldn’t be a surprise for users who trade in illegal services on shadowy marketplaces to find one day that their wallet has been emptied. You can’t cheat an honest man, the old logic goes. That’s especially true, Winter said, when comparing the libertarian-minded Silk Road (operated by a user known as Dread Pirate Roberts) and Evolution, which seemed to operate without a code of honor.

“Evolution was always mercenary. The thing about Silk Road was that it was a trust-based system,” Winter said. “With the Silk Road community you had Dread Pirate Roberts, with whom everyone was communicating and people knew his modus operandi. A lot of the people in the community are not a bit surprised that in this case they cut and ran.”

What happens next is anyone’s guess. The most logical outcome is that users who weren’t robbed will flock to Agora, another drug market that existed in the shadow of the Silk Road and then Evolution.

The long-term outcome is more obscure. Drug markets will likely remain unreliable because of their criminal nature until drug laws loosen or control of the sites falls to a community, not just an individual or select group of users.

“These will probably slowly transition into legal markets as the drug laws continue to change. That’s not to say there’s not shady activity going on, but there is room for legitimacy,” Winter said.

“The future of the markets is going to be decentralized systems. Those are going to come down to the honor system: Are you trying to deal just with people who are explicitly criminals or are you trying to be like the original Silk Road, where at least there were elements of idealism.”