Valera and Ledjo walked in shared silence, hand in hand, down the wide tarmac strip that doubled as road and pavement, and stretched from the centre of town to the small bungalow they called home. The buildings changed the closer they got, becoming more uniform until each one was identical to the last. The outskirts of Povenets B were made up of row after row of single-storey homes, with clapboard walls, flat shingle roofs, and five metres of empty scrub between them. Beyond the outermost row of bungalows stood two three-metre high fences, topped with barbed wire and patrolled day and night to stop anyone from entering or leaving.

Nestled in thick forest at the top of Lake Onega in the semi-autonomous region of Karelia near the Finnish border, Povenets B wasn’t on any maps. It was so secret it hadn’t even been found by the stray street dogs that were a permanent feature of towns and villages all over Russia. And if Povenets B looked like an internment camp, it was because that’s exactly what it had been. And in Valera’s mind it still was.

Povenets B had started life as a prison, a remote set of grey huts where members of the Karelian population who hadn’t sufficiently demonstrated their commitment to the Soviet cause were indefinitely interred. Since then it had grown in fits and starts. Larger, equally grey slabs of buildings were hastily erected; drab, prefabricated housing extended the original grid of prison blocks; basic roads were laid. Then the fence had gone up.

Povenets B was now a naukograd, a science city closed off from the outside world and administered by the GRU, the Soviet Union’s foreign military intelligence directorate.

As World War Two had given way to the Cold War, all sensitive state-sponsored operations like advanced scientific research, nuclear development, and weapons testing had been moved to secure locations across the Soviet Union. Some closed cities were little more than a factory with a few cabins for housing workers; others were entire cities, either built almost from scratch, like Povenets B, or simply redesignated, like Perm or Vladivostok, with fences and sentry posts surrounding them seemingly overnight.

Three years ago a member of the GRU had approached Valera outside Andrei Zhdanov University in Leningrad and made her the same offer that had been extended to a select group of academics across the country—to leave her low salary and cold apartment for the higher standards of living and unlimited research budgets of a naukograd. Facing another bitter winter in a draughty, underheated two-room home at the top of a housing block that somehow managed to bear the brunt of winds from the Baltic and the Arctic, Valera decided she couldn’t refuse. Along with fifty other families, she and Ledjo moved to Povenets B. She soon regretted her decision.