The secretary, Milly, had indeed come up with a stack of old preschool records. Forty years old, they were sheets of yellowed paper, some ruled into columns by hand, closely handwritten or typed, and kept in battered-looking box files. Somewhere there must be similarly dusty fossils of my own school career, I realized bleakly.

Ms. Gisborne riffled through the boxes briskly, running a manicured nail down rows of names. I could see she was getting nowhere. “There’s nobody with the surname Poole in here,” she said. “You can see I’ve looked a year or two to either side of—”

“Perhaps you could try another name. Casella.”

She frowned at me. “What’s that?”

“My mother’s maiden name. Maybe that was how she registered the child.”

She sighed and closed the box file. “I fear we are wasting our time, Mr. Poole.”

“I have the photograph,” I said plaintively.

“But that’s all you have.” She didn’t sound sympathetic. “There are many possible explanations. Perhaps it was a cousin, a more distant relative. Or simply another child, a playmate, with a chance resemblance.”

I struggled to say what I felt. “You must see this is important to me.”

She stared at me, an intimidating headmistress faced by an awkward student. But she turned back to the first of her box files and began again.

It took her five more minutes to find it. “Ah,” she said reluctantly. “Casella. Rosa Casella, first attended nineteen sixty-two . . .”

I found my breath was short. Perhaps on some level I hadn’t quite believed in the reality of this lost sibling after all, even given the photograph. But now I had a kind of confirmation. Even a name—Rosa. “What happened to her?”

Ms. Gisborne riffled through a couple of pages. “When she reached primary school age she was transferred—ah, here we are—to an English-language school in Rome . . .” She read on.

I sat there feeling, of all things, jealous. Why should this mysterious Rosa have had the benefit of an education in some fancy Roman school? Why not me?

Abruptly Ms. Gisborne dropped the pages back in the box file and closed it with a snap. “I’m sorry. This is too irregular. I shouldn’t be telling you this. The connection is only through what you claim was your mother’s maiden name—”

I guessed at another connection. “This school in Rome. Was it run by a Catholic order?”

“Mr. Poole—”

“The Puissant Order of Holy Mary Queen of Virgins?”

“Mr. Poole.” She stood up.