“What precise kind of murder do you fancy?” I asked. “Real, or fictional?”

“I’ve always been a fan of the truth,” he said with a thump of his cane.

“Who isn’t?” I squawked, too loudly. MI6 was missing out on a once-in-a-generation talent. But his face was calm and open. No traces of double meaning. I smiled and added, “Follow me.”

The back of the bookstore was a tight warren of blond-wood shelves, and smelled invitingly of yellowed pages and sixty years of shopkeepers making themselves a cup of tea. Right now, we had ample secondhand Agatha Christies, and I’d spent my first day here working on an intricate window display paying tribute to her lesser works; a day later, after that engendered some buyer interest, I’d enlisted Nick to help me rearrange the whole Mysteries and Crimes section. I’d become an expert in every flavor of murder we had to offer.

“Have you read this?” I said, handing him Ann Rule’s The Stranger Beside Me. “She worked with—”

“Ted Bundy,” he said, scoffing mildly. “Everyone’s read that one, love.”

“So I assume you’ve also read Helter Skelter, and In Cold Blood,” I said, poring through the shelves. We were in the section Nick called Enormously Famous American Murders (Brutal). He’d insisted on reorganizing the books first by where the murder happened, then by exceptionally specific genre, and then alphabetically. It had been a long night that nearly ended in Small-Town Royal Murder (Justified).

“Here’s a good one,” I said, scuttling past Assassinations and into Bloodless Crimes. “The Gardner Heist. No one dies, but there is a massive unsolved art theft.”

He chewed his lip, then nodded. “The wife does think I need a break from slashers.” He chuckled and zipped his cane through the air for emphasis.

I left him browsing the stacks, the book tucked under his arm, and took the long way back to finish up with my Wodehouse. Nick and I had gotten unbelievably lucky with this Airbnb, which allowed its tenants to live in a flat above the bookstore and run the business for the duration of their stay. It was typically full up years in advance—there are a lot of people in the world itching to play bookseller for a week—but there had been a last-minute cancellation. So after three weeks of skipping like pebbles across England, putting as much distance as we could between ourselves and the mess we’d left behind in London, we’d found a sanctuary: a short-term rental of what our lives might have been like if he’d been born plain old Nick, lover of bad snacks and worse TV, rather than Prince Nicholas, future king.

I ran my fingers idly across the spines of the books I passed. My twin sister, Lacey, had always hated used books; she wanted everything brand new, born into this world for her alone to make her mark on it. I’d never minded a little scruff. I liked that used books brought with them their own history—every dog-ear, every stain, every crease. Maybe a book was slightly faded because someone had left it in the sun on their honeymoon. Maybe page ninety-eight was turned at the corner because it contained a glorious insult, or the perfect romantic turn of phrase. Maybe the person who’d highlighted nearly every line had graduated at the top of her class. Secondhand books could have lived in tiny walk-ups or hotel rooms or the White House—or, here, even in Balmoral Castle itself. Each book was a mystery, its secrets hidden in plain sight.