I paused, and faintly smiled. “I wondered how long it would take before you brought that up. Who told you?”

“Need you ask?”

My mother, then. I looked more closely at the numbers, noting the most common ones were in the 60s. Probably the e’s, I thought. The letter used most frequently in English, after all, was e. It also was the letter we used most for ending words. If I was right about the placeholders, then two words in this cipher ended in 60-somethings, so again, they were most likely e’s. I took a pencil from my handbag. “So she’s told you all the details, has she?”

“Only that you handed in your notice,” Jacqui said. “You can’t keep doing that.”

“They wouldn’t let me work alone.”

“Most people in IT do work in teams.”

“I don’t.” And if the 60-somethings were all e’s, that meant it was the 6 alone that mattered, and the final digit didn’t count. Testing this, I tried removing all the final digits right across the board, from all the numbers, and put e’s where all the sixes were, and spaces for the placeholders. I ended up with:

10.e.18.18.e.17.space.8.12.18.e.17.1.e.16.18.e.4.

   space.5.17.2.12.1.e.space.21.12.19.2.5.e

There, I thought. Much less unwieldy. Right then. Twenty-six letters in the alphabet. Except if I were dealing with a simple substitution cipher, in which a was 1, and b was 2, and so on, then e would be written as 5 and not 6. I flipped e and f round, and got gibberish: Jerreq hlreqaepred fqblae ulsbfe.

Jacqui told me, “It would mean a trip to Paris. You like Paris.”

“In December?”

“Well, you wouldn’t have to go till after Christmas.”

“Even worse.”

She held her silence for a moment, then she said, “You’re right. You’d do much better staying here and moving back in with your parents. That would be a lot more fun.”

I wasn’t always good at detecting sarcasm, but in this instance just the words alone were all I needed to be certain she was teasing. Glancing up, I tried to straighten out my smile. “Ha-ha.”

“No, really. And your mother could invite young men to lunch on Sundays. You could have a lovely time.”

“I won’t need to move home,” I said. “I’ve got three months left on my lease. I’ll find another job.”

“This one would let you work alone. Besides, he pays obscenely well, you know, does Alistair.”

I shook my head. “I couldn’t take his money.” I flipped a few more letters, moving closer to an understanding of the patterns used by whoever had made this cipher. “This,” I said, “is really pretty basic, not so difficult. I’ve nearly got it. When I’ve finished here, I’ll let you have the key, and you can pass it on to him, and he can do all the deciphering himself, for nothing.”

“Yes, well, there’s one problem with your logic,” Jacqui told me.

“What’s that?”

“The code you’ve got there,” she informed me, “is not the one Alistair needs to have broken.”

My pencil paused, but only briefly, because I was too far along to just stop. “Then why do I have it?”

“It’s sort of a test. I told Alistair you were a wizard with codes and things, and he said if you cracked this one in under a week, he would not only hire you, he’d buy you a bottle of whisky.”

I wasn’t sure what letter had been flipped with r. The first word, with its double r, was likely my best clue. It might be meant to be a double l, perhaps, or double t. Since t was the most common English consonant, I went with that. Jetteq, read the first word now, unhelpfully. “He knows what this says, then?”

She nodded. “It’s out of an old book, or something.”

I had only two bits of the cipher left to unravel.

“Tell Alistair Scott,” I said, “that if he’s buying me whisky, my preference is sixteen-year-old Lagavulin.” I jotted the translation down and rotated the paper to slide it back over the table towards her.

I knew that I’d done it correctly when I saw her smile. That was how Jacqui always smiled when I did something to make her proud. “See? I was sure you could do it.”

“I’m not a real code breaker.”

“Sara.” She held up the paper. “You solved this in seventeen minutes. You’re good at it.”

Probably not good enough, said my inner perfectionist.

Jacqui, who’d known me so long and so well that she likely could hear that voice, too, said, “Come with me tomorrow, I’ll take you to meet him.”

“To Paris? Be serious.”

“Alistair Scott’s not in Paris.”

“But you said—”

“He only lives over the river, in Ham. It’s the job that’s in Paris.”

She asked me again to come meet him, and of course I told her yes, because I knew she wouldn’t let it go until I gave the answer that she wanted. But my gaze stayed on the paper in her hand while we were talking, and I wondered who had written it, and whom they’d meant to warn with those four words. Not me, I knew…and yet the final two words resonated, curiously:

Letter intercepted. France unsafe.

Chapter 2

I’d never been to Ham. It lay not all that far from the grand Tudor palace of Hampton Court, but on the opposite shore of the Thames, the south shore, where the river bent round on itself on its lazy way down into London.