“Tell me, Mara: What do you see here?”

I was still wiping my mouth and trying to gather my wits, trying to focus. Messenger’s cold-sounding question was hard at first even to comprehend. But I understood that this was some sort of test, and because I am ever the striver looking to excel, even when the object of the game is something I reject, I did my best to answer.

“He defended himself. Lost it. Oh, my God, killed that boy.” I took several deep breaths, tried vainly to slow the jackhammer insistence of my heart. “Is that the murder Manolo’s in jail for? He was defending himself!”

“Manolo’s fate is for human agency to determine. His doom will be pronounced by a jury and a court.”

I stared at Messenger in part because it was easier than watching the tragedy unfolding before us as Manolo was handcuffed, weeping, and Sneakers was taken away in an ambulance, his face swathed in bandages.

“We’re not here for Manolo?”

He shook his head.

Slowly it dawned on me. Manolo was in jail. Boots was dead. There was only one other.

“The other boy. The one in the sneakers.”

“The dead boy’s name is Charles,” Messenger said. “We are here for Derek. Derek Grady. Because as surely as Manolo, Derek is responsible for this death, yet he will not be arrested and he will not see any justice . . . but that which we deliver to him.”

WE TOOK A STROLL THROUGH DEREK GRADY’S life, much as we had done with Samantha. After an exhausting and dispiriting time of it, Messenger took us away to a place I’d never been but that I knew instinctively was important to my taciturn teacher.

My first thought was that Messenger had taken time travel to a whole new level. We were high atop a massive stone wall of such ancient creation that it was topped with crenellations and interrupted by slate gray-roofed conical towers.

Looking inward from the walls, I gazed across red-tile roofs, limestone walls, streets so narrow they could never have been meant for carriages, let alone cars. The wall curved far in both directions, enclosing this small village.

Gazing out from the wall, I saw a lazy river passing beneath an arched bridge of the same stone and vintage. But beyond that river was a much larger town, one still very much marked by history, but with cars and buses visible as well as satellite dishes and the other usual indicators of the modern era.

I turned away from that and studied the village within the walls and saw that here, too, were the signs of modernity, though less obvious: people talking on cell phones, electric lights shining from within narrow windows, tourist souvenirs spilling from the low doorways onto tight streets.

“Carcassonne,” Messenger said. Then, seeing my blank expression, added, “France.”

“Why . . .”

Messenger was peering down at the street, not with the casual appreciation of a tourist but rather like someone looking for something very specific. Hopefulness and wistfulness momentarily defined his features until he composed himself and regained the impassivity he wore as a mask.

“It’s beautiful, don’t you think?” he asked. “We see a great deal of pain. Beauty can be an antidote.”

It made sense, almost. But I didn’t believe him. He wasn’t here for a change of scenery. He was looking for something. Or someone.

“Tell me what you learned of Derek Grady,” he said, continuing to peer down into the town as he began to walk. He had long legs and walked quickly, in a hurry, searching. I had to rush to catch up. We were not alone on the wall—tourists passed by speaking half a dozen different languages—but as with doors and prison bars, they seemed to subtly relocate to avoid touching us. I was sure that we were quite invisible and inaudible.

“Derek’s a bully,” I said, thinking Messenger wanted the same economy of words from me that he practiced himself.

“More,” he said.

“Okay, he’s . . . well, he has a hard time in school, maybe because he doesn’t study very hard and maybe because he’s not very bright. He’s on the wrestling team, along with Boots. . . . That’s what I call the other boy, the one who died.”

“Charles,” Messenger said with a flash of anger. “Charles Francis Frohlick. That’s the name of the dead boy, a boy who was a bully and who may have grown up to be a worse bully, maybe a killer, even. But who might also have grown up to repent and change and to add something positive to this sorry world.”

“Charles,” I said, abashed at this passionate outburst. “Charles Frohlick. The dead boy. Okay, Derek and he were friends. Charles decided that Manolo was checking him out, in a sexual way.”

Messenger nodded, distracted now as he squinted down at someone passing by on the street. I followed the direction of his gaze. He was watching a girl, maybe seventeen years old, with auburn hair, long, wavy. The girl turned to look at something we could not see from our vantage point, and her face was clear in the spill of light from a doorway. Messenger had leaned forward, and now he retreated and could not conceal his disappointment.

“You’re looking for someone,” I said.

He did not answer.

“The girl Oriax mentioned. Ariadne.”

Both of his fists clenched and still he said nothing. Silence stretched between us as he began again to walk quickly along the battlement.

Was Ariadne a French name? Was Messenger French as well? Did such things as nationalities even matter to him?

“Continue,” Messenger snapped over his shoulder.