Chapter 4 The Suspicion

Margaret spent the next week investigating Thomas Webb's death, consulting with the local police, visiting the scene of the fire, and speaking to anyone who had known him. What she found was disturbing. Thomas Webb had been a brilliant mathematician, with a talent for pattern recognition that was unmatched at Bletchley. He had been working on a particularly difficult problem in the spring of 1942, a problem that had stumped several senior codebreakers. And then, in May, he had died in a fire that the police had ruled accidental. But Margaret had found inconsistencies in the official report. The fire had started in Thomas's bedroom, but there was no evidence of an electrical fault. The heating system had been turned off that night, and there was no sign of any other source of ignition. The police had concluded that the fire had been caused by a cigarette left burning on the bed, but Margaret had seen the evidence, and she was not convinced. She also discovered that Thomas had been working on something that he had not shared with his colleagues. He had been keeping notes, private notebooks that contained calculations and observations that he had not discussed with anyone. When the fire had occurred, these notebooks had been destroyed, taking Thomas's discoveries with them. But Margaret had found one of the notebooks. It had been hidden in the floorboards of Thomas's study, beneath a loose plank that he had not bothered to replace. The notebook contained a series of mathematical formulas and observations that were far beyond anything she had seen before. They were elegant, sophisticated, and deeply unsettling. They were also, Margaret realized, the work of a man who had discovered something he was not supposed to discover. Something that had gotten him killed. Margaret took the notebook to Commander Wright, who read it with growing alarm. He ordered Margaret to hand it over immediately, to turn it over to the security officers for further investigation. But Margaret refused. This is my evidence, she said. I found it. I have a right to keep it. Commander Wright looked at her with a mixture of frustration and concern. Margaret, you are in danger. This notebook could be the key to understanding who is behind this. But you cannot investigate this on your own. You need help. I have help, Margaret said. I have Dorothy. Dorothy Chen was a quiet, unassuming woman who worked in Hut 8 as a language specialist, translating Japanese communications that had been intercepted by Allied forces. She was Chinese-British, born in Hong Kong, and she had come to Bletchley in 1941 after the Japanese occupation of the colony. She was intelligent and hardworking, but she kept to herself, and Margaret had never been entirely sure what to make of her. Until now. Dorothy had agreed to help Margaret with the investigation, using her knowledge of languages and codes to analyze the notebook and the messages that had been sent to Margaret. She worked in secret, meeting with Margaret in the evenings after the other codebreakers had gone home, poring over the documents with intense concentration. And she found something that changed everything. The messages were not merely threats. They were part of a larger pattern, a code within a code that revealed the existence of a spy within the park. Someone was passing information to the Germans, someone who had access to the most sensitive intelligence and who was using that access to eliminate anyone who got too close to the truth. Thomas Webb had discovered the spy. And the spy had killed him to keep him quiet. Now the spy was coming for Margaret. The tension mounted as the deadline approached. Margaret knew that time was running out, that every hour brought her closer to the predicted date and the danger she had been warned about. She worked tirelessly, coordinating with her allies, gathering evidence, and preparing for the confrontation that she knew was coming. But Margaret had a feeling that Thomas Webb's death was not an accident. The second message had mentioned the dead, and Thomas Webb was the only dead man she could find who was connected to the codebreaking operation. She dug deeper, searching for any details about the fire, any witnesses, any inconsistencies in the official report. She found that Thomas had been working on something unusual in the weeks before his death—something that had attracted the attention of his superiors. He had been analyzing a series of intercepted messages that seemed to contain patterns that did not match standard Enigma traffic. When he had reported his findings, he had been told to stop investigating and to return to his regular duties. But Thomas had not stopped. He had continued his research in secret, and he had discovered something that someone did not want discovered. That evening she took the notebook to her quarters, locked the door, and read it again by the light of a shaded lamp. The formulas filled the first half, dense and beautiful, but the second half was stranger: columns of five-figure groups, each headed by a date, each annotated in Webb's tiny upright hand. Margaret knew the shape of those groups. She had spent three years pulling identical shapes out of naval Enigma traffic, and no mathematician arranged random numbers with that particular neatness. She copied three of the dates onto a blank sheet and set them against attacks she remembered from the hut's own summaries. The seventeenth of June 1941 sat beside a group she could now read in memory as the sinking of a freighter off Cape Finisterre. The twenty-second of September matched the loss of two ships from a Gibraltar convoy, ships whose positions, on the night they died, had been known to perhaps half a dozen people in England. Webb had not been doing mathematics at all, or not only mathematics. He had been proving that someone was selling positions, and he had dated every proof. The next morning Hayes stopped her on the path between the huts, cheerful under a sky the colour of wet slate. You look tired, Miss Chase, he said. The work never softens, does it. It does not, she replied. Neither does December. He smiled at that, and then asked, quite casually, whether she had found anything worth reading among Thomas Webb's old papers. Margaret felt the question settle somewhere beneath her ribs. She had told no one about the notebook, not even Wright in so many words. She answered that the police had taken everything of consequence, and watched him accept the lie the way a shopkeeper accepts correct change. After he had gone she stood in the cold until her fingers ached, replaying the sentence. Papers nobody official knew existed, offered back to her as small talk. That afternoon she cleared a cavity behind her own chimney breast, wrapped the notebook in oilcloth as Webb had wrapped his letter, and sealed it in with mortar borrowed from the gardener's shed. If fire was to be her ending, let it at least arrive with nothing worth burning. ---