“Me.” The word is barely more than a whisper. “He was supposed to kill me, wasn’t he?”

“Yes, Grace.” Ms. Chancellor tilts her head. “If you had never identified Dominic as your mother’s murderer, then you would have never been seen as a threat. But you did. And so you were.”

“He was meeting you, wasn’t he?” I ask her. “That night in the US embassy.”

Ms. Chancellor smiles. It’s like I’ve finally given her a reason to be proud of me. “He was indeed. That night Dominic came to tell me about his new mission, and together we tried to form a plan to keep you safe. Or safer. I’m sorry to say we weren’t as successful as either of us would have liked. He was going to leave the country and take you with him, but now … well, now our plans change once again.”

And then I think about Megan’s question — the one neither of us could ever start to answer.

“Why?” I stop, force Ms. Chancellor to turn back and study me. “Why did the prime minister want my mother dead?”

“That, my dear, is an excellent question. And one that — even after three years — we aren’t quite sure how to answer.” Ms. Chancellor takes a step toward a pair of double doors, but stops, her hands resting there. As if this threshold matters — this question matters. As if neither of us will ever be able to turn back.

“The one thing we do know,” Ms. Chancellor says, “is that it probably had something to do with her job.”

“Her job?” I have to laugh. “She was an army wife — an antiques dealer.”

Then it is Ms. Chancellor’s turn to smile.

“No, Grace. Your mother was those things, of course. But she wasn’t just those things. There were aspects of her life that she could never tell anyone. Not even you.”

When Ms. Chancellor pushes open the doors, I expect another room — perhaps another stretch of tunnel. What I see doesn’t make sense. There are more doors beyond the threshold. And more than doors. I recognize the gears and wheels — the same type of mechanisms that open and close the entrances to the tunnels that lay scattered throughout the city.

And there, in the center of all the wheels and gears, I see the same emblem that I have never really stopped to study before.

Ms. Chancellor places her hand on that emblem and pushes. Instantly, the gears spring to life. Turning, spiraling, shifting like a well-oiled machine. Sections of the wall begin to move, tumbling together one after another, until there is a great, round hole where the wall used to be.

I’ve been running around these passageways for days now. I know the low ceilings and musty-smelling corridors like I know the back of my own hand. But I don’t know anything, really, I’m coming to realize as I follow Ms. Chancellor through the great round hole.

The room that greets us isn’t even a room, really. It’s more like a cathedral, stretching out beneath the city. A high arched ceiling stands above a marble floor. And with one glance I can tell that it is old. No, not old. Ancient. I’m half afraid to follow Ms. Chancellor out onto the landing that sweeps around the massive room, overlooking rows and rows of books. One long stone wall is lined with weapons — swords and shields and spears. I look at Ms. Chancellor.

“You’re going to be okay, Grace,” Ms. Chancellor says, the words almost knocking me off-balance.

“I’m going to be okay,” I repeat, then grip the ancient railing in front of me, looking down into the past.

Ms. Chancellor holds out her hand, gestures for me to follow. “Come, Grace. There is so much for you to learn.”