‘Why bother to keep it at all?’ Vera whispers to Yuri, one morning, in menacing 2.00 a.m. wakefulness.

Yuri shrugs. ‘Perhaps Stalin has another use for it. Or perhaps he’ll prove the people don’t know what’s good for them. Perhaps he has plans to discredit the census with a follow-up study.’ None of which Yuri believes; he’s a mathematician, he knows the results are correct. It’s impossible to predict the General Secretary’s actions, but what is beyond doubt is that the data as it now stands undermines the Great Leader’s work.

While the census data is analysed and stored where no one can see or destroy it, those who have worked on it, particularly those in positions of responsibility, are far more exposed. The repercussions are felt almost immediately. In the first weeks after the census, several workers in Yuri’s division disappear. He is surprised at the choice of these targets.

‘They were middle-level,’ he says to Vera. ‘None was involved in the framing of the census.’

‘But perhaps they were among the first to identify a problem with the results.’

It’s another long night, Mikhail and Lidiya are asleep. Yuri and Vera are huddled together by the stove, trying to find patterns, reasons, explanations — not that reason has ever enjoyed top billing in explaining the workings of the Soviet leadership. Outside, winter rages. The window rattles, the wind howls, ice dashes against the glass.

‘These are only the first arrests,’ Yuri says softly.

The dark days grind on. Yuri is desperate to sever ties with the census and return to his old demography work. But without permission — and he won’t ask, won’t draw attention to himself — he must remain where he is. As one of the senior officers on the census, it is his task to apportion the questions to be analysed. It has come down from on high that if each analyst sees only one question, they’ll remain ignorant of the general thrust of the results. This is nonsense, but nonetheless Yuri, like everyone else, plays his part in the deception. The work is cloaked in secrecy; all those employed are aware that even a whisper could jeopardise not simply their livelihood, but their life. People are being arrested all the time, and as one of the leaders both in the planning and the analysis of the census, Yuri knows it’s only a matter of time before they come for him.

Whether at home or at work, these are perilous days. Yuri and Vera are watchful on the stairs, they’re watchful in the street, they’re watchful on trams and buses. Out in public, their conversation is empty; in shops, where informers are rife, they’re silent. Even where they believe themselves to be safe, they speak in whispers. Their voices became more and more hushed as the days stretch out of winter.