The Athenaeum Club stood on Pall Mall like a stern, grey-haired judge. Its columns were too perfect, its windows too clean, holding the night at bay with a glow of polished brass and old money. It was not a place accustomed to midnight intrusions by the Metropolitan Police.
Detective Inspector Thorne's warrant card did little to soften the posture of the night porter, a man whose disapproval was woven into the very fabric of his livery. The hack had been traced to a wireless access point in the Library, a wood-panelled sanctum where the only sounds were typically the rustle of the Financial Times and the gentle snoring of retired admirals.
"Access is strictly for members and their escorted guests," the porter intoned, as if reading from a tablet of stone.
"A man is dead," Thorne said, his voice a low, dangerous rumble that cut through the club's silence. "Two, in fact. The signal that helped kill them came from here. So you can escort us, or I can have twenty officers in here turning your precious library into a forensic suite. Your choice."
The library, when they entered, was a cavern of knowledge. It smelled of leather, pipe smoke, and privilege. The tech officer, a young woman named Chloe who looked wildly out of place with her rainbow-streaked hair tucked under a beanie, was already at work, her laptop plugged into a discreet wall socket.
"Got it," she whispered, her fingers flying over the keys. "Signal was a burst transmission. Lasted exactly six minutes. Came from this terminal." She pointed to a heavy, carved oak carrel tucked into a shadowy corner beneath a portrait of some glowering 19th-century statesman.
Elara approached it like a crime scene—which it now was. The carrel was empty, save for a green-shaded brass lamp and a pristine blotter. No book, no papers. She ran a gloved finger along the edge of the wooden surface. Not a speck of dust. It had been wiped.
"Who used it last?" Thorne asked the porter.
The man consulted a large, leather-bound ledger on the main desk. "The carrel was reserved from nine-thirty until eleven p.m. by Sir Robert Lancing."
The name hit the quiet room with a physical weight. Sir Robert Lancing: financier, philanthropist, trustee of the British Museum, and, as the evening news constantly reminded everyone, the leading contender to be the next Chairman of the BBC.
"Get him on the phone," Thorne said, his face grim. "Now."
While Thorne dealt with the impossible task of rousing a knight of the realm, Elara's attention was caught by the wastepaper basket tucked beside the carrel. It was lined with a fresh, white paper bag. Inside, empty. But as she looked closer, in the very bottom, she saw a single, crumpled ball of tissue. Without touching it, she used a pen to carefully lift it out and flatten it on the blotter.
The tissue was clean. But pressed into its delicate fibres was a faint, perfect imprint. The circular base of a small glass bottle, no more than two centimeters in diameter. And radiating from the centre, a tiny, almost microscopic pattern of lines.
She took out her phone, switched on the torch, and held it at a raking angle. The light cast shadows in the impressions.
"Chloe," she said softly. "Can you photograph this with maximum resolution?"
As Chloe worked, Thorne ended his call. "Sir Robert is at his country house in Wiltshire. Has been all evening. Dozens of witnesses, including the Archbishop of Canterbury, apparently. His membership card hasn't been used here in a week."
"So someone used his reservation," Elara said, her eyes fixed on the tissue. "Someone who knew his habits, had his access codes, or had the influence to have them provided. Someone who wanted the hack to point directly at one of the most powerful men in the country."
"A misdirection?" Thorne frowned.
"Or a message. 'Look how high this reaches.'" She pointed to the pattern on the tissue. "This is the base of a vial. An old apothecary's vial. See the pattern? It's a stylised caduceus. The symbol of Hermes, patron of… among other things, thieves, liars, and alchemists."
"Invisible ink," Thorne realized.
"A very specific, historically accurate recipe," Elara confirmed. "Probably gallnut extract and ferrous sulfate. It would be clear when written, darken with age or, in this case, when exposed to the specific wavelength of your UV lamps. He mixed it here. Tested it. Wiped the vial clean and disposed of the tissue." She looked around the hallowed room. "He didn't just borrow a terminal. He used this space as his laboratory. He felt at home here."
Chloe let out a small, sharp breath. "Guys? I enhanced the image." She rotated her screen. The high-resolution photo showed not just the imprint of the vial, but, caught in the fibres at the very edge of the tissue, three minuscule, crystalline fragments. "I ran a quick elemental analysis from the spectral reflection. It's salt. But not just table salt. It contains traces of calcium sulphate and magnesium chloride."
"Sea salt," Elara said. "Evaporated from a specific mineral environment. Archaeological grade. You could source it, trace it to a particular region."
Thorne's phone buzzed. He listened, his expression hardening by the second. "We have to go. Now."
"What is it?"
"The dagger from the first scene. The Roman pugio." He looked at Elara, a storm in his eyes. "It was deaccessioned from the Museum's collection three months ago. Sold at private auction. The buyer was a shell company. The curator who authorized the sale and signed the export licence…"
He didn't need to finish. The pieces connected with a sickening click.
"Professor Alistair Finch," Elara whispered. The second victim. The man with the witch-hunter's book on his chest. He hadn't just known the killer. He had, in some way, supplied him. He was part of the chain.
As they hurried out of the silent club, back into the pulse of the city, the case fractured and re-formed in Elara's mind. It wasn't a simple series. It was a web. The killer wasn't just a scholar. He was a curator, assembling a collection. And his exhibits were the dead.
The taxi door slammed shut, sealing them in a bubble of yellow light and grim revelation.
"Finch provided the dagger," Thorne said, thinking aloud. "The killer used it in the first murder, then killed Finch in the second. Why? Punishment for a poor acquisition? A ritual completion?"
"Or a logical progression," Elara said, the theory forming from the dark clay of the evidence. "Think of the Codex not as a book, but as a recipe. Finch supplied an ingredient—the authentic Roman blade. Once it was used, its purpose was fulfilled. The one who supplied it became… redundant. Or worse, he became the next necessary ingredient. The scholar who understands the witch-hunt becomes the subject of a witch-hunt parable."
She saw it now, the terrifying symmetry. The killer was operating on a logic that was impeccably historical, impeccably symbolic, and utterly deranged. He was following a script written in blood and time.
"He's not just killing people, Marcus," she said, staring out at the sleeping city. "He's footnoting them. And we don't have the index."
The taxi turned a corner, the lights of New Scotland Yard looming ahead. Somewhere in the vast, dark library of London, a killer was turning a page, selecting his next citation. And Elara knew, with a cold, scholarly certainty, that they were already running late for the next chapter.