Denise, predictably enough, said, “You have been too long in this one room. You need a change of scene. Your brain can’t work without fresh air.”

Which from a scientific standpoint was debatable, I knew, but her suggestion of a change of scenery struck me suddenly as something that might be a good idea. Often when I labored on a tricky bit of programming, I found if I switched tasks to something simpler for a little while, my brain had time and space to better concentrate upon the more important problem.

And ever since it had been first suggested to me Sunday morning, there was one much simpler task I’d added to my list of things that needed doing. “Is it very difficult,” I asked Denise, “to get from here to Saint-Germain-en-Laye? Is there a train?”

She nodded. “Yes, the RER. But you don’t have to take it. I can drop you on my way, it isn’t far. I’m nearly ready. I just have to make a phone call first, then we can go. All right?”

The cat Diablo stared down from his perch atop the box of files and dared me to.

“I’ll get my coat,” I said.

Chapter 10

Denise drove fast, and played the radio—both things I found distracting, but today I was distracted even more by my imaginings.

The road to Saint-Germain-en-Laye looked much like any other road, but I was busy seeing it the way it would have been when Mary Dundas and her brother had presumably set out that afternoon from the house of Sir Redmond Everard. In Mary’s time—I’d worked it out—a horse and chaise could travel at an average speed of 1.65 leagues an hour, to use the standard reckoning for leagues in Paris, every district having its own measurements. And Chatou, from its center, lay approximately 1.7 leagues from Saint-Germain-en-Laye, which meant it would have taken Mary and her brother, in the winter, just above an hour to reach their final destination.

In the car, it took us fifteen minutes. Slightly less, the way Denise was driving.

We crossed the river by a long bridge, turned and wound our way around and up a road still edged with the remainder of the old town walls, then back along an avenue with trees cut in a box-like hedge and round again to where the old château sat facing down the huddled buildings at the center of the town. There was a church directly opposite with regal steps and pillars that looked every bit as old as the château, and both those buildings had retained their grandeur—but the modern world had crept right to their doorsteps.

Denise had pulled in to what looked like a long bay for buses to pick up and drop off their passengers. Pointing ahead she said, “There is the entrance. Or if you don’t want to go inside just yet, go through there, through that big gate, and down and around through the park and along the terrace—the long path overlooking the river. It’s really a beautiful walk, and the fresh air will help you change your thoughts,” she said, using the French phrase for clearing one’s mind. With a glance at her wristwatch she asked, “Will two hours from now be enough time?”

I wasn’t about to impose my own schedule on hers. “Tell me what time I need to be back here, and I’ll be here.”

“Three o’clock,” she said. “Be back at three.”

I said, “Thanks,” as I climbed from the car and she gave me a wave and was off again. The broad stretch of pavement in front of the château was practically empty, which suited me fine. I had never done well in the jostling confusion of crowds.

The château rose squarely in front of me, solid and soaring, designed to impress, yet it looked slightly lost. Like the house at Chatou it seemed fully aware that it should have had grander surroundings; as though it had slumbered and woken to find itself here at the edge of a street crowded round with tall mansard-roofed buildings, an outdoor café and the broad entrance into the underground RER station bookending the church on the opposite side, and it wasn’t quite sure how to manage the fact that the world had moved on.

It was built of that same pale stone that looked ivory in some lights and golden in others and gave French châteaux their own beauty. Today there was no sun to make that stone glow, only clouds in a flat winter sky, and the walls of the château thus robbed of their light had a dull ochre cast to them, only relieved by the contrasting red brick that trimmed the round walls of the turrets and towers and framed the tall arched rows of windows that lined the two uppermost stories, reflecting no image but that of the overcast sky.

Hardly welcoming, but then the point of my trip here today wasn’t to be made welcome. It was to learn the layout of the château and the grounds, to walk where Mary Dundas had once walked, so if I ever broke her cipher and began to read her diary entries I could understand them better.

Alistair considered it unlikely Mary’s brother and his wife and children would have lived within the château proper, because most of the apartments there were taken up by influential Jacobites and those who’d served the young King James’s mother while she’d lived. It was more probable, thought Alistair, that Nicolas Dundas on his return to Saint-Germain-en-Laye would have found lodgings for his family in the town that had grown up around the château walls to house the varied tradespeople and servants and supporters of the exiled royal court. But even so, the château and the people who had lived there would have been a daily feature of the life of Mary Dundas, and whatever events she described in her diary would need to be placed against that backdrop to be viewed in proper context.

I used my mobile now to take a few snaps of the château. When I got back to Chatou, I could create a file of photographs to reference when I was transcribing the diary. There, I thought. Pure optimism. Jacqui would be proud of me. She always told me I was far too quick to give up hope.