The descent was stunning. Chris Tarbell, a special agent from the New York FBI office, was in a window seat, watching a green anomaly in a sea of blue as it resolved into Iceland's severe, beautiful landscape. On approach to Keflavík International Airport, he could now see the city of Reykjavik coming into view. And just beyond that, perched on the edge of a moss-covered lava field: the massive matte-white box that housed the Thor Data Center. That's why Tarbell and two US attorneys had come all this way. Thor was the home of a computer with a very important IP address, one that Tarbell and his FBI colleagues had discovered back in New York—the hidden server for a vast online criminal enterprise called Silk Road.

They'd been working on this case for months, as had federal agents across the country, in a wide-ranging digital manhunt for Dread Pirate Roberts: the mysterious proprietor of Silk Road, a clandestine online marketplace that functioned like an anonymous Amazon for criminal goods and services. Silk Road investigations had been launched by Homeland Security, the Secret Service, and the DEA office in Baltimore, where an agent named Carl Force had been working an undercover identity as a Silk Road smuggler for more than a year.

Tarbell and his team—known as Cyber Squad 2 (or CY2 for short and "the Deuce" for fun)—were relative newcomers to the case. The other agencies had dismissed the FBI, partly because of interagency bluster and partly because the traditional agents who thought casework was all guns and grime and grit had no respect for the eggheads from cybercrime. But in the midst of this enormous law enforcement effort—mostly fruitless so far—Tarbell and CY2 had found the first promising lead in the case.

Cybercrime agents spend a lot of time at their desks, and it was exciting to be in the field. Down below they could see Iceland's fierce geology, all jutting rock built up from the water by volcanoes. Beneath the surrounding ocean are the massive cables that make the country an important location for web traffic; the island is nearly equidistant between North American and Europe, and its forbidding geography and climate reduce cooling costs and provide free geothermal power. One of the attorneys told Tarbell about Iceland's tectonic forces—the North American and Eurasian plates, slowly tearing open a growing chasm. Really puts you in your place, Tarbell thought.