Bettys tea shop, Osla had said over the telephone. Tomorrow, two o’clock. We’ll talk.

Bugger that, Mab had told her, ringing off with a bang, and gone to check on the children.

Eddie was a warm, soft weight against Mab’s breast as she lifted him from his bed. He was fretful, fussing from his nap, but he settled quickly against her. She inhaled the smell of talcum and little boy, wondering if he was heavier than he’d been just last night—he was growing so fast, eighteen months and already bigger than most two-year-olds. He’d be a six-footer for sure. Mab tiptoed out of the nursery, passing a hand over Lucy’s dark head. Luce was a restless sleeper, kicking her sheets off and muttering, but she stilled at Mab’s hand on her hair.

Mab fed Eddie downstairs, avoiding the peas he tried to spit out onto her cream linen blouse, but afterward as she set him down to play with the toy train his father had made for him, she couldn’t settle. She stood turning an unlit cigarette between her fingers—she was trying to quit—stomach churning as Beth’s cipher message echoed through her mind.

There couldn’t have been a traitor at Bletchley Park. Candidates were vetted before they were even invited to interview; when she transferred from the bombe machines to the mansion, Mab had heard about the boxes and boxes of MI-5 files in Hut 9. And if there was a traitor, who were they selling to? BP had remained safe, secret, and successful throughout the war, which argued against the Germans’ ever having found out.

No. The cipher message’s accusation was either a madwoman’s paranoid fantasies or the lies of a desperate woman willing to say anything to get free. Either way, what happens to me if I help her? Mab thought. Beth was locked up on the government’s orders; communicating with her could be a violation of Mab’s oath. “Receiving and encouraging insecure communications of privileged information” or however they might phrase it—but it could mean prison.

Mab looked around her quiet sitting room. This home, this family, this life, was everything young Mabel Churt from Shoreditch had ever dreamed of. Her house with its three stories of mellowed Yorkshire stone and its surrounding garden of bramble roses. Her marble-tiled bathroom crowded with perfume vials and cosmetics, rather than a shared toilet down the hall. Her own bank account, with a balance she no longer compulsively checked to make absolutely certain there was enough for the electric bill, for Eddie’s new shoes, for Lucy’s future education. Her husband.

Risk all of this, risk her family, risk a cell—for Beth, who had betrayed her during the war?

What did she risk to ask for your help? the thought whispered. What is she risking now?

Six Years Ago

May 1941

Chapter 23

Out with it, Beth,” said Mab.

Beth blinked, holding the red silk petticoat she’d tiptoed into the room to return, and so did Osla, who sat buffing her nails by the light of a candle stub. The three of them had only just sneaked back in from the dance, absolutely knackered, long past Mrs. Finch’s lights-out, and mentally Osla was already totting up the next Bletchley Bletherings: What shy filly splashed out at the Bedford dance this weekend? Even the most brilliant brain needs a little Glenn Miller to invigorate the old gray matter, and BP’s boffins certainly sat up and took notice . . .

“You danced five times with Harry, Beth.” Mab turned away from the glass where she’d been brushing her hair and fixed Beth with a stern eye. “All slow swoony tunes, too.”

Beth closed the bedroom door as Boots trundled in on her heels. “We were talking shop. You know . . .” Codebreaking, Osla knew she meant but wouldn’t say, even here in private.

“Cheek to cheek?” Osla couldn’t help saying.

Beth looked puzzled. “Yes. So no one could overhear.” Back in her high-necked nightdress with her hair combed out of its waves, she looked very much the colorless wallflower who had never been on a date in her life.

Osla sighed. “Don’t tell me you’ve gone moony over Harry Zarb.”

Beth looked horrified. “We’ve worked together, that’s all. He’s good at what he does, I’m good at what I do, it’s easy to talk . . .”

Osla and Mab exchanged glances.

“That’s called getting moony.” Mab tossed her brush down. “High time you started looking about for a fellow, Beth, but don’t settle for a married man giving you a line.”

“There was no line.” Beth reached for the end of her plait to fidget with, but it was no longer there. “He didn’t—try anything. He only asked me to dance so we could talk safely, no one hearing.”

“Only at BP.” Mab settled on her own bed in her nylon slip. “Not ‘Let me whisper sweet nothings in your ear’ but ‘Let me whisper ciphers in your ear.’ It doesn’t mean it still wasn’t a line, Beth.”

Osla wasn’t sure. Was Harry really the sort to step out when he had nice, tired-looking Sheila at home looking after their frail son in his leg braces? She wasn’t so worried he would try things on with Beth—more like, Beth would get all starry for the first man who flirted through “Moonlight Serenade” without meaning anything serious by it.

“You can never predict what kind of man steps out on his wife,” Mab said as though reading Osla’s mind. “That’s why you steer clear of all married men. Because it starts as a harmless friendship, and then you’re hearing how their wife doesn’t understand them and they’re going to leave her soon, and then you’re sneaking off behind the wife’s back until things get sorted, which they never do. It’s all rubbish. I’ve never got into that situation,” she added, seeing the look on their faces. “But I’ve known girls who did, and their stories all turned out the same—not at the altar. Because the men were just looking for a bit of you-know.”

“Bit of what?” Beth asked, perched on the edge of Osla’s bed.

“You know.” Mab looked at her. “Don’t you?”

“No . . .”

Osla stared down at her hands. “Actually,” she heard herself saying, “I don’t, either. About . . . It.” She could barely get the words out, but she couldn’t lie either. Not in this blackout-curtained bedroom with two girls she’d worked with and wept with and shared untold fears with for the last year.

“Come off it!” Mab scoffed. “I’ll believe that Beth here never learned the facts of life from Mrs. Finch—though didn’t your sisters tell you, after they married?” she demanded, sidetracked.

Beth looked blank. “They said never to let a boy kiss me until we were engaged, so I thought maybe kissing made you pregnant.”

“Methodists,” Mab muttered, and looked at Osla. “All right, I believe Beth, but I don’t see how you can possibly be in the same boat considering that racy mother of yours, you dizzy deb.”

“Don’t call me that.” Osla flared, knowing she was being oversensitive, not particularly caring. She was tired, tired, tired of climbing an endless ladder where she thought she’d finally reached a rung where she’d never be called dizzy deb or silly socialite again, only to find it still ringing in her ears, classifying her as dim-witted, inconsequential, ignorant. Only when it came to this, she was ignorant, no getting around it. You could spend your days translating Hitler’s personal telegrams and still be an utter ignoramus in other spheres. “You think my racy mother ever told me anything, Mab? I grew up surrounded by hirelings. Nannies taught me to wash behind my ears; boarding school taught me German grammar; finishing school taught me to make a court curtsy. My mother was too chuffed getting married, getting divorced, and getting remarried to notice I was there, much less teach me the facts of life. So I know nothing, and none of the girls I went to school with did either, because everyone’s mothers were too terribly proper to get into the whole nasty subject.”

Mab still looked skeptical. “The day we met, you embarrassed a pervert on the train by asking if he needed to hide the tent in his trousers—”

“You think I had any idea what I was talking about? I fake being terribly worldly, darling, but it’s all flimflam.” Osla looked down at her hands again. “At the Savoy last year, I was telling a friend that I wished my boyfriend wouldn’t carry his torch in his front pocket when we danced, and this old dowager at the next table rears back and hisses at me, ‘You silly fool, don’t you know what an erection is?’ And I laughed like I knew what she meant, but I had not the foggiest. And now I’m twenty years old and in love, and I still have no idea how It happens.” Osla ran out of breath, finally looking up. “I hate being such a—a silly deb. Can you just enlighten me?”

“Why do you think I know all about it?” Mab looked peculiarly still in the light of the candle stub. “Because Shoreditch girls are tarts?”