an attorney before deciding to join the government. She was the portrait of a hardworking Midwesterner—friendly and under- stated, but relentlessly disciplined. “I was a first child, a rule fol- lower,” she said. She was attracted to the DEA by the idea of catching doctors and pharmacists who had betrayed their oaths.

Holdren had spent his whole career in law enforcement, also entering the DEA at thirty-three after stints as a Border Patrol agent and an investigator in the U.S. Office of Personnel Manage- ment, where he conducted national security background checks. Both investigators were familiar with the basics of tracking Web pharmacies, having undergone an online investigation course as part of their thirteen-week training at Quantico. Called Basic Tele- communications Exploitation, it covered how to use the Internet to build a case using controlled buys.

Long before the national opioid epidemic began making head- lines, the DEA had become concerned with the proliferation of prescription drug sales online, and the potential for Web pharma- cies to funnel dangerous medication onto American streets. But in their first few years at the DEA, Brill and Holdren both found themselves attacking what they felt was the outer edge of the prob- lem. They would bust one online pharmacy, only to find that an- other had sprung up in its place. Like a pair of city cops who only picked up corner dealers, they weren’t making a dent in the crimi- nal organization supplying the drugs to the street.

Brill and Holdren had been talking for a while about finding a case to work together, fifty-fifty, something that would go beyond local pharmacy raids. “We were trying to get to the head of the beast,” as Brill put it. “Somebody had to be paying, and some- body had to be profiting greatly. And they needed help running such a large operation. I don’t think we knew. It could be any- body.”

Now, buried in the lines of the spreadsheet on Brill’s screen were the outlines of a case unlike any that they had ever seen.

There were hundreds of thousands of entries, and they weren’t just shipments from one mom-and-pop pharmacy in Chicago. In-