Hut Six, Midnight

Evelyn read Thomas's letter at her desk in Hut Six at quarter past midnight, when the others had gone on break and the only sound was the wind against the windows and the low mechanical hum of the Bombe in the next room working through another naval Enigma key.

She should not have brought a personal letter to work. She'd done it anyway.

What does it cost you to not be able to say.

She set the letter face-down on her desk and picked up the intercept she was meant to be working through — a Wehrmacht logistics message, four days old, already losing tactical value but useful for the pattern analysis her supervisor had assigned her unit. She was good at pattern analysis. She was good at most of it, actually, better than she'd expected when they'd recruited her out of Cambridge in the autumn of 1941, a history student with a talent for crosswords and a security clearance that had arrived in an envelope with no return address.

The work mattered. That was the thing she held onto on the bad nights, the nights when the messages she was decoding told her exactly how many ships had gone down, how many men were in which positions, how thin the lines actually were. She knew things that almost no one else in England knew. She carried them without anyone to tell, without any way to explain why some mornings her hands shook over her tea.

She turned Thomas's letter back over.

He was perceptive. She'd noticed that at the dance — the way he'd watched her deflect without commenting on it. Most men commented.

She pulled a sheet of paper from her drawer and began to write.

Dear Thomas,

You asked what it costs. I'm not going to answer that exactly, but I'll give you this: I work with information. A great deal of it. Most of it I cannot discuss. Some of it I carry home at night and cannot set down, because I've seen enough to know the war can be lost and enough to believe it won't be. Those two things sit in the same chest and that is where I live.

You're perceptive. I noticed that at the dance. It's the reason I gave you my address.

Write when you can. I'll write back.

— Evelyn

She sealed it before she could revise it. She walked it to the outgoing post herself.

At two in the morning, working through a new intercept from the eastern sector, she caught a reference — a unit designation she hadn't seen before, an oblique mention of American coordinates. She flagged it and moved on.

She didn't know yet that she should have stopped.