Leo was due to stay in Washington DC for a few days, depending on how the work progressed. Resigned to the fact that his time in the United States had been suddenly and dramatically cut short, he was impatient to return to New York – there was now intense pressure on his investigation. In all likelihood he had weeks, not months, before the Soviet Union took further action against his daughters. If they went as far as to arrest Zoya and Elena then he would not be able to hold out – more likely, he would begin to make arrangements to return that same day. A once benign trip to the archive was now a costly distraction.

A friendly man called Simon Clarke had met him at the airport, introducing himself as the archivist, an owlish-looking individual in his fifties with round gold-framed glasses and a gently protruding stomach curving out from his body like a pleasant hillside. He spoke fluent Russian, grammatically perfect, but with an American accent and Leo guessed that he’d probably spoken to very few native Russians. Kind and mild-mannered, Clarke hoped that Leo could illuminate many of the discoveries that had been collecting dust, mysteries that they’d failed to unravel about Soviet espionage protocols launched against the main adversary. Clarke had used Soviet spy slang – the main adversary> – keen to show that he was acquainted with their secret code.

On a brief tour of the city, before heading to the archive they stopped outside the FBI headquarters. The building was modern, concrete, quite unlike the Russian secret police headquarters, the Lubyanka, with its grand historical facade in the centre of Moscow. The architectural principle of the Hoover Building seemed not that it should appear impressive but that it should appear unbreakable. There was nothing ornate or decorative about the design: it was a hybrid of a parking lot and a power station, as if the FBI were in the same utilitarian category. The archive, not marked on any map or listed in any official registry, was located three blocks back, on 8th Street. There was no sign, no reception, merely an unremarkable door that opened directly onto the street like a fire escape. The entrance was sandwiched between two large offices: a door without a number or mailbox, like a magical portal that everyone on the street walked past oblivious to the secrets it held.