FADE IN: INT. HUT 6, BLETCHLEY PARK, NIGHT A single desk lamp burns against blackout curtains. The room is long and narrow, a converted stable block that still smells faintly of hay beneath the cigarette smoke and machine oil. Wooden trestle tables run the length of the space, each bearing stacks of paper, pencil stubs, and ashtrays full of Senior Service ends. Most of the desks are empty. The night shift belongs to the skeleton crew. DR. ELEANOR CHASE (32) sits at the third desk from the door. She is thin in the way that women who forget meals are thin, her dark hair pinned back with two grips that are losing the fight. Her cardigan has ink stains on the left cuff. Her eyes move across a sheet of five letter groups with the focused velocity of someone reading music. On the desk: a ruled pad covered in her handwriting, a slide rule, a frequency chart pinned to a wooden board, and a chipped mug of tea gone cold two hours ago. She writes a sequence of letters. Crosses it out. Writes another. Pauses. Returns to the intercept sheet and traces a line of cipher groups with her pencil tip, lips moving without sound. From the adjacent room, the rhythmic clatter of a Type X cipher machine being operated by a WREN in uniform, visible through the connecting doorway. The girl is nineteen, maybe twenty, typing with the mechanical precision of someone who has done this for twelve hours.