The Lock-Keeper's Cipher
A 1930s Canal Spy Thriller

About this book:

On the mist-shrouded Grand Union Canal, the water moves slow—but secrets travel fast. Thomas Finch tends Lock Seventeen with the quiet competence of a man who has spent twenty years measuring his life in coal dust, creaking oak gates, and the rhythm of narrowboats. But beneath his woollen cap lies a sharper mind: Thomas is a cipher clerk for a shadow branch of British intelligence, decoding messages hidden in the daily shipping registry. When a folded scrap of greaseproof paper yields a warning about a legendary operative called "Greyman" moving south, the canal's placid surface shatters. Someone has been in Thomas's cottage. Someone has scraped clean his official ledger and rewritten the boat names—poisoning the very key he uses to decrypt the truth.

Now the past is rising with the tide. *The Falcon*, a ghost boat vanished three years, has slipped through his lock unseen, its passage erased and replaced with a fiction. The forgery is perfect, mimicking Thomas's own hand—meaning the traitor knows the cipher, knows the network, knows *him*. As the autumn fog thickens and a young boy on a passing butty slips him a message he dare not read aloud, Thomas must navigate a conspiracy that stretches from the Coventry coal pits to the Admiralty in Whitehall. Every lock-keeper on the cut is a potential asset—or a liability. Every barge horn in the night could be a signal. And the next entry in his secret diary might be his last.

Atmospheric, intricate, and steeped in the gritty poetry of England's vanishing waterways, *The Lock-Keeper's Cipher* transforms the humble canal into a artery of espionage where the current runs deep and the stakes are national. For readers who love the tradecraft of le Carré, the historical texture of Alan Furst, and a protagonist whose greatest weapon is a windlass and a pencil, this is spy fiction at its most immersive—where the quietest waters hide the deadliest currents.