For years, AT&T’s San Francisco office was just another cog in the corporate machine—a glass-and-steel fortress of broadband bureaucracy. Employees shuffled in and out, eyes fixed on monitors, hands busy ensuring America’s internet traffic flowed without a hitch. But behind one nondescript door, labeled only “641A,” the telecom giant was harboring a secret so explosive it would rip a hole in the illusion of digital privacy.
Mark Klein wasn’t the kind of guy to go looking for trouble. A seasoned AT&T technician, Klein had spent over twenty years ensuring the company’s networks functioned smoothly. He was methodical, focused, the kind of worker who took pride in making sure that when people fired off emails or streamed their favorite shows, everything worked as it should.
