On today’s episode of Decoder, I sat down with Joseph Cox, one of the best cybersecurity reporters around. Joseph spent a long time working at Vice’s tech vertical Motherboard, but last year, after Vice imploded, he and three other journalists co-founded a new site, called 404 Media, where they’re doing some really great work.

Somehow, on top of all that, Joseph also found time to write a new book coming out in June called Dark Wire: The Incredible True Story of the Largest Sting Operation Ever, and I can’t recommend it enough. It’s basically a caper, but with the FBI running a phone network. For real.

Criminals like drug traffickers represent a market for encrypted, secure communications away from the eyes of law enforcement. In the early mobile era, that gave rise to a niche industry of specialized, secured phones criminals used to conduct their business.

Joseph’s done a ton of reporting on this over the years, and the book ends up telling a truly extraordinary story: After breaking into a few of these encrypted smartphone companies, the FBI ended up running one of these secure phone services itself so it could spy on criminals around the world. And that means the FBI had to actually run a company, with all the problems of any other tech startup: cloud services, manufacturing and shipping issues, customer service, expansion, and scale.

The company was called Anom, and for about three years, it gave law enforcement agencies around the world a crystal-clear window into the criminal underworld. In the end, the feds shut it down in large part because it was too successful — again, a truly wild story. Now, with the rise of apps like Signal, most criminals no longer need specialized hardware, but that, of course, raises a whole new set of issues.

The book is a great read, but it also touches on a lot of things we talk about a lot here on Decoder. There really are bad people out there using tech to help them do bad things, but the same tools that keep their communications private help give everyone else their privacy, too — whistleblowers, dissenters, ordinary people like you and me.

There’s a deep tension between privacy and security that constantly runs through tech, and you’ll hear us really dig into the way tech companies and governments are forever going back and forth on it. There’s a lot here, and it’s a fun one.