The holy month of Muharram is a dangerous time in Pakistan. It marks the beginning of the Islamic calendar but is also a period of mourning for Shiite Muslims. Each year, in the overflowing metropolis of Karachi, they take to the streets in processions by the thousands to observe Ashura,the anniversary of the martyrdom of Hussein ibn Ali, the Prophet Mohammed’s grandson, and one of the holiest days of the year for Shiite Muslims. It is often a bloody affair, and not just because of the ritual self- flagellation in which many of the devout partake. Over the past four years, with astonishing punctuality, Shiite processions and mosques have been brutally attacked by Sunni supremacist militants bent on starting a sectarian war.

In 2009, two bombs exploded along the parade route, splattering the concrete street with human entrails and shredded clothing, and killing 43. The following year, on November 11, the Pakistani Taliban drove a car bomb right up to Karachi’s elite counterterrorism Crime Investigation Department, destroying the building and killing 18. And in late November 2012, in Orangi Town neighborhood, two bomb blasts killed five people, as the city’s undaunted Shiites continued with their mourning processions.

Understandably, Karachi’s streets were tense on the ninth night of Muharram last year, as final preparations were being made for the Ashura festivities. Nervous government officials had cut cell phone service across the city for 11 hours that day, hoping to prevent attacks. Some 10,000 police officers had been dispatched to the main parade route, though in a city with an estimated 20 million people, even this show of force was only a drop in the bucket.

As night fell on Saturday, November 24, the deputy superintendent of police, Zameer Abbasi, was out making the rounds. He had decided to take one last patrol when he received a phone call around 9:20 pm about a small explosion at a nearby apartment building. “My first thought was that this might be a high-value target, a terrorist who had planned to target the procession but had made a mistake with the bomb,” Abbasi later told me. When he arrived at the scene, smoke was pouring from a third-floor apartment window.

Abbasi didn’t wait for the bomb squad to arrive. He quickly cordoned off the street and raced inside, fearing that there might be more explosives or a suicide bomber. When he got to the apartment, however, the scene was unlike anything he had seen before. A red chemical had been sprayed across the white walls. There was what seemed to be a laboratory: conical flasks connected by rubber tubing, sacks and boxes labeled with the names of chemicals, a small centrifuge. A silvery blue powder was spilled across the bathroom floor, and blood-red footprints crisscrossed the living room. “I thought this might not be the kind of blast I thought it was,” Abbasi said. “It looked like some kind of chemical reaction had happened.” He didn’t know it at the time, but he had just made the first bust of a Pakistani meth lab.

It’s hard for an outsider to understand the pace of change in Karachi these days. Statistics don’t really do it justice. But here’s one: From 2000 to 2010, Karachi’s population grew more than 80 percent. That’s roughly equivalent to adding more than New York City’s entire population in just a decade. (For all the talk of the staggering boom of Chinese metropolises, the world’s next fastest-growing city —Shenzhen — grew only 56 percent, adding fewer than 5 million people.) Over the past decade, millions of Pakistanis have fled the fighting and terrorism in their country’s northwest to settle in Karachi, Pakistan’s pulsing commercial heart — home to banks and corporations, shipping and transport, entertainment and arts. But the flood of migrants in search of jobs and opportunity has also brought Karachi some less savory additions.

Gangs tied to political parties have long operated in the poorer parts of the city, running extortion rings and land-grab schemes. More recently, Pakistani Taliban militants have also gained a foothold in the city, carving out territory in neighborhoods like Manghopir, where they run criminal and smuggling rackets, rob banks, and administer a cruel and terrifying justice. From restive Baluchistan province, in Pakistan’s west, a war economy driven by more than a decade of conflict in Afghanistan has opened Karachi and its ports to narcotics and weapons smuggling. Pitched firefights that go on for days between gangs, or between gangs and the police, are not uncommon.

As a result, Karachi is far and away the world’s most dangerous megacity, with a homicide rate of 12.3 per 100,000 residents, some 25 percent higher than any other major city. Consider this telling statistic from a megacity next door: In 2011, 202 murders occurred in Mumbai, India. Karachi had 1,723 — and more than 2,000 in 2012. Now added to this combustible mix are drug gangs often with links to Iran — like the one Abbasi and his men busted. And they’ve brought with them a new commodity that is increasingly making its way from Karachi’s ports to the wider world: methamphetamine.

Opiates had always been Karachi’s drug of choice. With as much as 90 percent of the world’s heroin production right across the border in poppy-rich Afghanistan, Pakistani drug barons have reaped the benefits of proximity. Despite a ban on opium production in 1955, Iran saw a heroin resurgence in subsequent decades, becoming a major regional production center. But after the mullahs came to power in 1979, the drug trade shifted east. Heroin was produced en masse in Afghanistan and Pakistan to fund the mujahideen fighting the Soviets. The drugs primarily went to market through Karachi’s port and on to Europe and the Americas.

Setting up the infrastructure for this trade was almost a matter of policy for military ruler Gen. Muhammad Zia-ul-Haq, who created the National Logistics Cell — essentially a military trucking business — to transport heroin from the northwest to Karachi and bring weapons in the other direction. Even by the standards of rogues and dictators, Zia was unusually brazen and corrupt, with close associates implicated in drug trafficking and money laundering plots. Pakistan seemed on the verge of becoming a narcostate. In 1980, on his way to the United Nations in New York, Zia’s diplomatic cargo was searched, and heroin was reportedly found stuffed into marble lamps. After the war with the Soviets and Zia’s mysterious death, that transport infrastructure was more or less privatized by Pakistani cartels and drug mafias, and it has lasted through the present day. Today, as much as 40 percent of Afghanistan’s heroin still transits through Karachi, according to the United Nations.

But as the global appetite for heroin has waned, producers and smugglers are turning to methamphetamine, demand for which is soaring in nearby East Asia. Iran has emerged as the biggest producer of methamphetamine in the region, but Pakistan still appears to be the natural transit route to eastern markets like Malaysia and Australia, as well as a major supplier of the precursor chemicals that are the drug’s main ingredients. There are signs, however, that sophisticated labs are being set up in Pakistan itself, perhaps by Iranian syndicates. And links to Pakistani meth are showing up in places from Mexico to Melbourne.

As anyone who has seen the TV drama Breaking Bad knows, the production of methamphetamine is a complex and combustible process, requiring a laboratory and various chemical ingredients, or precursors — the most notable of which is ephedrine or its close cousin, pseudoephedrine. These precursors have legitimate uses in cough, cold, and allergy medications (they act as a decongestant), and drug companies produce them on an industrial scale. But in Karachi, which has an advanced pharmaceutical industry, it has become clear that production is being diverted to criminal enterprises.

In April 2011, Karachi port officials discovered 540 pounds of ephedrine hidden in packets of spice mix bound for Australia. That same year, officials in Tehran reported the seizure of 1,170 pounds of ephedrine coming from Pakistan. And in June 2012, a group of men with more than 1,750 pounds of meth was stopped at Karachi’s airport. Authorities only managed to arrest one of the smugglers; accomplices waiting outside barged into the customs hall and fled with the drugs. But what really has international drug-control officials worried is the sense that these seizures are just the tip of the iceberg. For example, Australian police are investigating a Melbourne biker gang, the Black Uhlans, that is suspected of setting up a massive Indian meth lab and contacting a senior Pakistani government official about drug importations.

The UN International Narcotics Control Board (INCB) helps governments regulate and monitor the potential for illicit drug production, and Pakistan, like most countries, reports its need for ephedrine — what are called annual legitimate requirements. In 2007, Pakistan reported a legitimate requirement of 11 tons of pseudoephedrine to the INCB. In 2010, it reported 53 tons — nearly three times the amount that most countries produce, making Pakistan the world’s fourth-largest producer of pseudoephedrine. That means that either a lot more Pakistanis have suddenly come down with the sniffles — or the drug trade has, once again, corrupted officials at the highest levels.

In September 2012, former Prime Minister Yousuf Raza Gilani’s son, Ali Musa, was arrested for allegedly pressuring officials, with help from the country’s health minister, to increase ephedrine quotas for two pharmaceutical companies. One of these firms, Berlex Lab International, which was granted a license to produce some 14,300 pounds of ephedrine, claims it sold its tablets to a company called Can Pharmaceutical. But according to an Associated Press report: “[I]nvestigators discovered the address for the company was a residential house in Multan, and nobody answered the door. The owner of the company didn’t answer his phone.” No wonder that prosecutors speculated that the ephedrine was destined for meth labs in Iran. (Gilani maintains his innocence, and his lawyer claims the accusations were politically motivated.)

Worryingly, the trend appears on the rise. The INCB notes that in 2008, Iranian authorities dismantled two meth labs; in 2010, that number had spiked to 166. That year, Pakistani officials reported four seizures of smuggled ephedrine, totaling 585 pounds, near the border with Iran, as well as more than 14 tons of diverted cold medicine, according to the U.N. Office on Drugs and Crime (UNODC). Matt Nice, of the INCB’s secretariat in Vienna, said that the size of some of the recent seizures of ephedrine originating in Pakistan suggests that a significant portion of legitimate cold medicine gets diverted to the black market. “If the [declared annual requirement] is so high that 500 kilograms can go missing, then that means you have something that’s probably already been infiltrated,” Nice told me.

A person familiar with the Gilani case, who requested anonymity, citing the ongoing investigation, explained how the scam allegedly worked. “You register yourself as a pharmaceutical company,” he said. “Then you register yourself for a chemical like ephedrine. Then you get a quota for ephedrine on an export order, and then you say, ‘Can I have this converted to local consumption because my export order has fallen through?’ And then I take that, I falsify my distribution documents, and I have it smuggled.” At many steps along this path, he said, it’s necessary to bribe officials and bureaucrats to sign documents and deflect attention.

Corruption has a long, sordid history in Pakistan, but drugs add an extra layer of societal corrosion. On paper and anecdotally, evidence suggests that the meth trade is already having a deleterious impact on a country that doesn’t need any more problems. Drug use, particularly of opiates and cannabis, is already high in Pakistan, with 1 percent of the population using heroin and 4.1 million people thought to be drug-dependent, according to the UNODC. But a 2013 report issued by the UNODC and the Pakistani government notes that a “detectable emergence of methamphetamine use has been found in certain areas of the country.… This finding is noteworthy because it is the first time a study has generated data relating to the use of amphetamine-type stimulants” in Pakistan. Just as the transport of massive amounts of heroin through Pakistan inevitably created a local market, and millions of addicts, the new focus on methamphetamine has led to a metastasizing trade on Karachi’s streets.

Crystaal,” as it’s pronounced, is everywhere, from the city’s upscale neighborhoods to the poorer sections, like Lyari. The crime-ridden south-central district is Karachi’s fiercest, a dense network of slums housing some 1 million people. It’s basically a no-go zone for law enforcement. Police generally need to ask permission to patrol and must negotiate entrance with the district’s crime boss: Uzair Jan Baloch, the head of the now-banned People’s Aman Committee, a gang cum political party cum philanthropic organization. When police attempted an operation in Lyari this past April, Baloch’s men held them at bay for days under a hail of bullets until the police retreated. In late July, an elite police ranger unit raided Baloch’s mansion; he had disappeared into the night.

In Manghopir, a violent, impoverished slum in Karachi’s north, the users are easy to spot. “I’ve seen these guys start banging their heads against a wall; they become out of control. It’s like they are numb and don’t feel pain,” said a community activist who asked to remain nameless due to numerous threats from the Taliban and gangs. “Now heroin is ending and crystal is taking over.” A gram of crystal goes for anywhere from 500 to 800 Pakistani rupees — roughly $5 to $8. That’s still more expensive than heroin, but users say the high is more intense. Most of the young men whom the activist sees tweaking in the streets are foot soldiers for Baloch’s gangsters: “The gangs hire the kids, get them addicted to crystal, and then make them do crimes when they are high so they have no fear. Then they pay them with more crystal.”

Just two weeks after Pakistan’s general elections this spring, I visited one of Karachi’s largest drug-rehabilitation programs, the Drug Free Pakistan Foundation (DFPF), which treats around 4,000 addicts annually. The DFPF’s headquarters are on a quiet street in the leafy Gulshan-e-Iqbal neighborhood, a middle-class area ruled by the Muttahida Qaumi Movement, a secular political party that dominates politics in Karachi. The party’s red, white, and green kite-shaped posters and painted slogans still adorned nearly every light pole and wall. Like all the major political parties here, though, it has an armed wing, and like the rest, it profits from an intimate relationship with criminal activities.

Approximately 1.2 million drug addicts, the majority of whom are heroin users, live in the city, said the foundation’s director, Farheen Naveed. Beginning in 2010, however, she has seen an influx of meth addicts seeking help at DFPF. As we toured the foundation’s headquarters, she noted the uptick. At the end of May, 35 of the 101 patients in DFPF’s treatment center in the industrial neighborhood of Landhi were there for meth abuse. “The numbers at the facility today are actually much higher than I was expecting,” Naveed said.

If Karachi’s police seem helpless to combat drugs on the streets, perhaps Pakistan’s Anti Narcotics Force (ANF) is the last, best hope to stem the large-scale trade and trafficking. Staffed by former military officers, the ANF is in practice a branch of Pakistan’s powerful army, but it has received funding from the United States and guidance from the U.S. Drug Enforcement Administration (DEA). Its more than 1,500 well-armed troops form the front line in the drug war, and the force’s website trumpets the staggering quantities of hash and heroin seized: 9,863 pounds of hash apprehended on May 1 in Killa Abdullah, 613 pounds of heroin on April 26 in Karachi. And on July 26, the ANF announced that its Lahore office had seized some 117 pounds of ephedrine, 95 pounds of ephedrine mixed with vanilla powder, and, bizarrely, 1,272 bottles of ephedrine mixed with jam. Often, though, the news releases accompanying such successes contain a line of boilerplate that speaks to the scale of the problem: “Although the endeavors of ANF are wholehearted and wide-ranging, the meager strength / resources remains to be a challenge.” According to Naveed, “The crackdown on ephedrine has not had an impact on the prevalence of crystal use on the streets; it continues to rise.”

Pharmaceutical executives in Karachi, however, say that the ANF has cracked down hard on access to ephedrine and pseudoephedrine, so much so that companies are afraid to apply for new quotas. Insiders say that this is blowback from the Gilani case: ANF officials are embarrassed that they didn’t catch the scam themselves, and in an attempt to show their underwriters that they are serious, they have overreacted — but will soon back off. The labs and the traffickers are likely biding their time, waiting to see whether the ephedrine spigot is easily loosened again. “I think that there is such easy money to be made [by diverting ephedrine] that I don’t think it’s going to go away,” said a former official. “It’s like bootlegging.”

One year before Ali Musa Gilani was charged in Islamabad, another young Pakistani man was arrested for his alleged role in selling ephedrine on the global black market. Shiraz Malik, then 34, was taken into custody last year after landing at Prague’s airport on a flight from Dubai. He was later extradited to the United States, where he awaits trial in a federal court in California. Malik is accused of running a multimillion-dollar “industrial scale” online narcotics and precursor business, according to the U.S. attorney in California’s Eastern District.

Undercover DEA agents found a website for a Karachi-based pharmacy that offered to ship a number of prescription opiates as well as ephedrine, according to a criminal complaint the DEA filed against Malik. After agents emailed the pharmacy, Malik is alleged to have written back offering to send samples of his wares via express mail. Between 2008 and 2011, Malik mailed everything from heroin to ephedrine powder to Ritalin. The agents wired tens of thousands of dollars to bank accounts associated with Malik in the United States and Europe. After accessing his email account, the agents found that Malik had done regular ephedrine business with customers in Mexico. (They also found photos of kilogram-sized bags of ephedrine packed in suitcases that were believed to be headed to Mexican customers. The shipment never made it. A Pakistani-American mule was arrested with the cargo as he attempted to fly to Mexico City.)

Malik has pleaded not guilty. But there is still what appears to be an online business directory listing for the pharmaceutical wholesaler — Shama Medical Store — that the DEA alleges was a front for Malik’s operation. In the section for company information, the site reads: “we are abal to provide u any kind of medicion and any kind of row material all our tha world, and we also doing drop shipping all or tha world.” There’s even a physical address, located in Karachi’s Hijrat Colony neighborhood, which was described to me by an urban-rights activist as “a nursery of crime” controlled by a powerful drug gang known as the “Hamid Terha Group” (terha roughly translates as “crooked”).

I decided to pay Shama Medical a visit this past spring and see whether I’d be able to get prices for ephedrine or bulk amounts of cold medicine. I brought along a friend who covers crime for a local newspaper, and we made our way to Hijrat Colony slum, which is bordered by railway yards to the east and a mangrove swamp to the west. We took a main thoroughfare near the port into the colony and were quickly squeezed to a standstill by the suddenly winding, narrow streets. We doubled back, stopping to ask for directions.

Finally, we pulled up to Street 56, got out of the car, and walked into an alley.

After a couple of hundred yards we reached a four-story concrete building with faded red paint that read, “Shama Hospital.” Next door was Shama Medical Store. Both seemed abandoned except for a group of young toughs loitering in the shade outside. One of them, with a long beard and wearing a white T-shirt and jeans, asked us what we were looking for; the others just gave us hard stares. “Shama Medical Store — is it open?” my friend asked haltingly. In the silence, I realized that the street, in the middle of a densely packed slum, was unnervingly empty.

“Yeah, it’s here. But it’s been closed for a long time,” the bearded guy said — just as an older man in a purple button-down shirt, gray suit pants, and pointy black dress shoes that looked to be made of imitation alligator stepped out of the medical store. A cell phone was pressed to his ear.

We should go, I whispered under my breath. So we did — walking quickly back to the car and driving away, hoping we wouldn’t be followed.

Later, through a well-sourced local contact, I inquired about whether the police and ANF had investigated Shama Medical. They said they had never heard of it.

This article was reported in partnership with The Investigative Fund at The Nation Institute, now known as Type Investigations.