Knox poured himself a drink and tried to make sense of it. The coroner now believed they had died closer to seventy-two hours before being discovered, which explained the slick liquid Knox had seen around their noses and mouths—it was lung fluid, expelled as rigor mortis started to wear off. The marks on the men’s necks suggested they’d been choked to death, but on closer inspection their windpipes showed no signs of being crushed. Toxicology tests were being run but the results would take another day to come through.

So, Knox didn’t know anything about the two dead men beyond the most basic information. He didn’t know how they’d been killed, or why. It was hard for him not to feel like Manning was setting him up.

Chapter 7

Chapter 7

In her cramped, windowless lab, Valera thought about the lie she’d told Zukolev.

She didn’t need the argon. He was right—it was inert. It didn’t do anything. It wasn’t a catalyst and it had nothing to do with her research. She’d just requested the gas because she wanted to know how much attention Zukolev was paying to her work.

She was telling the truth about something else, though. She really did feel close to a breakthrough. After years of struggle, toil, and setbacks, she was convinced she was on the edge of glory—because she had to be.

Valera’s father had had two passions in life: early Asian languages, and British detective stories. Every evening when Valera was a child, he would read the Russian translations of novels by Arthur Conan Doyle to her. She was too young to understand the complicated plots, but one line from The Sign of the Four—the novel they had been reading the night her father was seized by the NKVD and never seen again—had been seared into her mind. The Russian translation was ‘when you have removed every other possibility, the truth is all that’s left’.

After three years of wrestling with the same problem every day, she’d eliminated so many possibilities that, by Conan Doyle’s logic, she must be near the answer.

‘What shall we try today?’ she asked the portrait of Stalin hanging on the wall opposite her.

Zukolev insisted that a portrait of the great man hung in every office and workroom in Povenets B, so the city’s workers could always feel him looking down on them. It was always the same portrait, and always shrouded in black velvet.

But to Valera the face hanging in her office didn’t belong to Stalin. It was her lab assistant, her collaborator, her confessor. His identity changed day by day, depending on what Valera needed to keep herself sane—another little rebellion.