Aetius sat in his favorite basket chair, sipping beer. “Yes, yes … the same law on an equal footing. The law is above all of us — the landowners, the senators, even the Emperor himself, whoever that is right now. That is the genius of the old system, you see. It doesn’t matter who is in charge. It is the system itself that has spread so far and sustained itself, even though we have had soldiers and administrators and even emperors chosen from among those who would once have been called barbarians. The system persists, while we come and go.”

Standing there, holding the fragile papyrus in her hand, she said, “Like an anthill. The Empire is like an anthill, and we are all just ants, running around.”

He slammed his wooden tankard down on the arm of his chair. “Ants? Ants? What are you talking about, girl?”

“But an anthill organizes itself without anybody telling it what to do. And even when one ant dies another takes her place — even the queen. That’s what the Greeks say, and they studied such things. Isn’t your Empire just like that?”

“Rome is not an anthill, you foolish child! …”

So they argued on, both aware of and enjoying their roles, she mischievously provoking, he spluttering and snapping —

The door was thrown open with a crash.

In the doorway, framed by darkness, stood a soldier. He staggered into the room, visibly drunk. When he saw Regina he grinned.

Aetius seemed as shocked as Regina. But he took a step forward. “Septimius,” he said, his voice like thunder. “You’re drunk. And you should be on watch.”

Septimius just laughed, a single bark. “Nobody’s on watch, you old fool. What does it matter? I haven’t been paid. You haven’t been paid. Nobody cares anymore.” He took a lurching step into the room. He was still staring at Regina, and she could smell the drink on his breath. He was, she remembered, the soldier who had exposed himself to her when she bled on the Wall.

She backed away, but she found herself pressed against the table and, in the confines of this little chalet, couldn’t retreat any farther.

Aetius took a measured step forward. “Septimius, get out of here before you make things much worse for yourself.”

“I don’t think I will be taking any more floggings from you, old man.” He turned to Regina. “You know what I want, don’t you, miss? You’re just ripe for the plucking—” He reached for her. Regina flinched away, but Septimius grabbed her small breast and pinched it hard.

Aetius barreled into him, shoulder-first. Septimius was slammed against a wall, and the whole chalet shook with the impact. Aetius staggered upright. “You keep away from her, you piece of filth—” He hurled his fist, his mighty fist like a boulder.

But Septimius, drunk as he was, ducked underneath the punch. And as he rose, Regina saw a flash of steel.

“Grandfather — no !”

She actually heard the blade go in. It rasped on the coarse wool of Aetius’s tunic. Aetius stood, staring at Septimius. Then dark blood gushed from his mouth. He shuddered and fell back, rigid, to the floor.

Septimius’s mouth dropped open, as if he were aware for the first time of where he was, what he had done. He turned and ran into the night. Aetius lay on the floor, breathing in great liquid gurgles.

There was blood on the floor, blood pooling as it once had from her father’s body. Regina forced herself to move. She ran to Aetius, and lifted his heavy head onto her lap. “Grandfather! Can you hear me? Oh, Grandfather!”

He tried to speak, coughed, and brought up a great gout of dark blood. “I’m sorry, little one. So sorry.”

“No—”

“Fool. Been a fool, fooling myself. It’s over. The Wall. They’ll leave now, the last of them. No pay, you see, no pay. Cilurnum fell, you know. You saw the fire on the horizon. Cilurnum gone …” He coughed again. “Go with Carta.”

“Cartumandua—”

“Go with her. Her people. No place for you here. Tell her I said …”

She asked the question that had burned in her young heart for five years. If he died, he could never answer it, she might never know. “Grandfather — where is my mother ?”

“Rome,” he gasped. “Her sister is there, Helena. So weak, that one. Wouldn’t even wait for you …” He grabbed her shoulder. His palm was slick with blood. “Forget her. Julia doesn’t matter. You’re the family now. Take the matres.”

“No! I won’t go. I won’t leave you.”

He thrashed in his spreading pool of blood, and more crimson fluid gushed from the ripped wound in his chest. “Take them …”

She reached out and grabbed the little statues from their shelf in the lararium. At last he seemed to relax. She thought he wanted to say more, but his voice was a gurgle and she could make out no words.

Suddenly something broke in her. She pushed away his head, letting it fall to the floor, and ran to the broken doorway, clutching the statues. She looked back once. His eyes were still open, looking at her. She fled into the night.

Somewhat to my surprise, the head of Saint Bridget’s, the school Gina had attended, was welcoming, initially anyhow. She listened to my tale of the photograph, though she was obviously skeptical about my story of a missing sister.

She had me sit in her office, on an armchair before her big polished desk. Ms. Gisborne was a slim, elegant woman of maybe fifty-five, with severely cut silver-gray hair. Over a business suit she wore a black academic gown lined with blue — the school colors, as I vaguely remembered from my sister’s day. The office was well appointed, with a lush blue carpet, ornate plasterwork around the ceiling, a trophy cabinet, a large painting of the school on the wall opposite big windows, lots of expensive-looking desk furniture. It had the feel of a corporate boardroom; perhaps this sanctum was used to impress prospective parents and the local sponsors that seem essential to the running of any school these days. But an immense and disturbingly detailed Crucified Christ hung from one wall.

My chair, comically, was too low. I sat there sunk in the thing with my knees halfway up my chest, while the head loomed over me.

She didn’t remember Gina — in fact, Ms. Gisborne was actually about the same age as my older sister — but she had taken the trouble to find some of her reports. “She came over well: a bright, pretty girl, natural leader …” The kind of thing people had always said of Gina. But she held out little hope of tracing any record of any younger sister, and clearly thought it odd that I should even be asking. “There was a preschool department here in those days — for the under-fives, you understand — but it has long since closed down. The school’s gone through a lot of changes since then. I’ll see if Milly can find the records, but I’m not optimistic. It’s all so long ago — no offense!”

“None taken.”

While we were waiting for the secretary to go down into the dungeons, Ms. Gisborne offered me the choice of a coffee, or a quick tour of the school. I felt restless, embarrassed, foolish, and I knew I would quickly run out of conversation with the headmistress of a Catholic school. I chose the tour. I had a little trouble hauling my bulk out of the tiny chair.

Out we walked.

The school was a place of layered history. A frame of two-story Victorian-era buildings enclosed a small grassy quadrangle. “We encourage the students to play croquet in the summer,” said Ms. Gisborne lightly. “Impresses the Oxbridge interviewers.” The corridors were narrow, the floor hardwood with dirt deeply ground in. There were immense, heroic radiators; huge heating pipes ran beneath the ceiling. We walked past classrooms. Behind thick windows rows of students, some in blue blazers, labored at unidentifiable tasks.