“I JUST can’t bear this any longer,” writes “Megan” in an anonymous internet forum. Waiting for online shopping to be delivered is frustrating. But for drug users it can be agony. Megan’s vice is OxyContin, an addictive prescription painkiller. Like many users, she buys her illicit supply on the “dark web”, a hidden corner of the internet accessed with anonymous browsing software. In the past month the online market for drugs has been rattled, after the two main drug-dealing sites suddenly locked buyers and sellers out. “If you know anyone...who would sort something out for me tonight or tomorrow I’ll drop dead of gratitude,” pleads Megan.

The illegal-drugs trade, worth perhaps $300 billion a year, has been creeping onto the web. Like other online retailers, drug dealers can undercut the high street by spending less on maintaining a physical presence and employing salesmen. Consumers like the convenience and safety of shopping from home, and online product reviews are especially useful when buying potentially deadly substances. Bitcoin, a near-untraceable digital currency, covers their tracks. One in seven American drug users have ordered a fix online, according to one survey.

This was all upset on March 18th when Evolution Marketplace, the Amazon of the dark web, vanished in a puff of pixels. Unlike Silk Road, shut down by the FBI in 2013, Evolution seems to have been taken down by the people who ran it. In a brazen “exit scam”, the site’s anonymous administrators apparently made off with up to $15m in Bitcoin payments that they were holding in escrow.

A few days later, users reported that Agora, the next-biggest drug-peddling site, was inaccessible. Amid rumours of another scam, its administrators reassured buyers and sellers that they were simply carrying out technical upgrades. A rush of users migrating from Evolution may have put its servers under strain. The site has also suffered “denial of service” attacks—by law enforcers or rival dealers, no one is sure. After a wobbly Easter weekend, Agora is back, for now.

Together, Evolution and Agora were responsible for 82% of online drug listings, according to the Digital Citizens’ Alliance, which monitors illicit online markets. Each was bigger than Silk Road ever was. A dozen smaller players, such as Nucleus Marketplace and Black Bank, stand to benefit from their problems.

The recent trial of Ross Ulbricht, Silk Road’s creator, showed how deeply police have infiltrated the dark web. This is bad for business: though punters don’t much fear arrest, they are wary of being ripped off, and better law enforcement increases the incentive for administrators to shut up shop and run off with the loot, says James Martin, a criminologist at Macquarie University in Australia.

Back in the online forum, another user suggests to Megan that if she can’t get hold of OxyContin online, she could ask local dealers for heroin, which satisfies the same craving. What’s more, he observes, “it’s available in any country that has streets”. It is also far deadlier. Driving drug users off the web and onto the backstreets carries risks.