Garrett was handcuffed and led through passport control, where his ID was seized. Fingerprints, mug shots, and DNA swabs followed. He was eventually led to a holding cell and then an interrogation room. There he was not formally charged but was informed that he was being investigated for burglary, property destruction, and criminal trespass, among numerous other possible charges. He was told he had been the subject of a manhunt by the British Transport Police. His alleged crimes were a blatant affront to the image of a high-tech security state London had constructed for itself. And yet, during his interrogation, an investigator leaned across the table and whispered: "Off the record, Bradley, I love the work that you do."

Despite his scholarly bona fides—his doctoral work in geography at Royal Holloway, University of London had garnered wide acclaim—Garrett scarcely looks the part of an academic, neither tweedy nor fusty. Thirty-two years old, with a trimmed goatee and a mop of straight brown hair hanging over black plastic frames, he grew up in Southern California and ran a skate shop before deciding to pursue a doctorate. His face, which is frequently lit up in mischievous, eyebrow-raised delight, still bears the pocks of over a dozen piercings he dispensed with in the interests of maintaining some veneer of academic respectability.

*How’s This for a To-Do List? * Bradley Garrett tells us his team’s dream targets.

1. Gwangmyong Ghost Station, North Korea.

"Apparently North Korea has a metro system in Pyongyang and, even better, an abandoned station hidden in its depths."

2. Fordlandia, Brazil.

"Henry Ford built this Michigan-style company town to harvest rubber from the Brazilian jungle in 1928. It’s now a ghost town.

3. Metro-2, Russia.

"This Moscow metro system was rumored to have been built by Stalin to transport the Soviet elite to the Kremlin, a secret airport, and a town beneath Ramenki. It’s guarded by guys with machine guns. We want in."

4. The Statue of Liberty Torch.

"Accessible via a fifty-four-rung ladder in the arm. And if we can’t take the ladder, we’ll shoot an arrow tied with fishing line up to the torch from the crown and rig ropes like we did at the Angel of the North in England. Game on."

But it was his doctoral research itself that was perhaps most punk rock. His dissertation in human geography, which he had defended the previous year, was entitled "Place Hacking." The title came from his argument that physical space is coded just like the operating system of a computer network, and it could be hacked—explored, infiltrated, re-coded—in precisely the same ways. He conducted a deep ethnographic study of a small crew of self-described "urban explorers" who over several years had infiltrated an astonishing array of off-limits sites above and below London and across Europe: abandoned Tube stations, uncompleted skyscrapers, World War II bomb shelters, derelict submarines, and half-built Olympic stadiums. They had commandeered (and accidentally derailed) an underground train of the now defunct Mail Rail, which once delivered the Royal Mail along a 23-mile circuit beneath London. They had pried open the blast doors of the Burlington bunker, a disused 35-acre subterranean Cold War-era complex that was to house the British government in the event of nuclear Armageddon. The London crew’s objective, as much as any of them could agree on one, was to rediscover, re-appropriate, and reimagine the urban landscape in what is perhaps the most highly surveilled and tightly controlled city on earth.

The catch-all term for these space-invading activities is "Urbex," and in recent years it has grown as a global movement, from Melbourne to Minneapolis to Minsk. The Urbex ethos was, in theory, low-impact: no vandalism, no theft, take only photographs; as one practitioner put it, "a victimless crime." Urbex is staunchly anticommercial (Converse was widely mocked in the scene when it released an urban-exploration-themed sneaker), and yet has an undercurrent of self-promotion, with many explorers selling their photographs to the media or publicizing them on blogs and web forums. Despite some initial skepticism about the legitimacy of the topic by his university advisers, Urbex proved to be a rich avenue of inquiry for Garrett—far better than his initial plan to study modern-day Druids. But in the course of his research Garrett had gone native in a big way, acting both as a scientific observer of a fractious subculture and an active participant in their explorations. And he made no excuses for that. "The whole definition of ethnography is that it’s participation," he told me. "You go out and you interact with people, and you live with them, and you understand their lives."