“You’re going to have to talk to me,” she said. “Master Simon is dead, Sir Rowley’s laid up. I need someone who thinks to help me find the killer-and you’re a thinker, Ulf, you know you are.”

“Yes, I bloody am.”

“And don’t swear.”

More silence.

He was using a float, a curious contraption of his own invention that ran his line through a large bird’s quill so that the bait and tiny iron hooks were kept to the surface of the water.

“I missed you,” she said.

“Huh.” If she thought that was going to placate him…but after a while he said, “Do we reckon as he drowned Master Simon?”

“Yes. I know he did.”

Another trout rose to a worm, was unhooked, and thrown into the creel. “It’s the river,” he said.

“What do you mean?” Adelia sat up.

For the first time, he looked at her. The small face was screwed up in concentration. “It’s the river. That’s what takes ’em. I been asking about…”

“No.” She almost screamed it. “Ulf, whatever…you mustn’t, you must not. Simon was asking questions. Promise me, promise me.”

He looked at her with contempt. “All I done was talk to the kin. No harm in that, is there? Was he a-listening when I done it? Turns hisself into cra and perches on trees, does he?”

A crow. Adelia shivered. “I wouldn’t put it past him.”

“That’s dizzy talk. You want to know or not?”

“I want to know.”

He pulled in his line and detached it from rod and float, arranged both carefully in the wicker box that East Anglians called a frail, then sat cross-legged facing Adelia, like a small Buddha about to deliver enlightenment.

“Peter, Harold, Mary, Ulric,” he said. “I talked with their kin, the which nobody else seems to have listened to. Each of un, each of un, was seen last at the Cam here or heading for un.”

Ulf lifted a finger. “Peter? By the river.” He lifted another. “Mary? She was Jimmer the wildfowler’s young un-Hugh Hunter’s niece-and what was she about, last seen? Deliverin’ a pail o’ fourses to her pa in the sedge up along Trumpington way.”

Ulf paused. “Jimmer was one of them rushed the castle gates. Still blames the Jews for Mary, Jimmer does.”

So Mary’s father had been among that terrible group of men with Roger of Acton. Adelia remembered that the man was a bully and, quite probably, easing his own guilt for the treatment of his daughter by attacking the Jews.

Ulf continued with his list. He jerked a thumb upriver. “Harold?” A frown of pain. “Eel seller’s boy, Harold’d gone for water as to put the elvers in. Disappeared…” Ulf leaned forward. “Making for the Cam.”

Her eyes were on his. “And Ulric?”

“Ulric,” said Ulf, “lived with his ma and sisters on Sheep’s Green. Taken Saint Edward’s Day. And what day was Saint Edward’s last?”

Adelia shook her head.

“Monday.” He sat back.

“Monday?”

He shook his head at her ignorance. “You frimmocking me? Washday, woman. Mondays is washday. I talked to his sister. Run out of rainwater to boil, they had, so Ulric was sent with a yoke o’ pails…”

“Down to the river,” she finished for him in a whisper.

They stared at each other and then, together, turned their heads to look toward the Cam.

It was full; there had been heavy rain during the week; Adelia had shuttered the window of the tower room to stop it coming in. Now, innocent, polished by the sun, it fitted the top edge of its banks like sinuous marquetry.

Had others noticed it as a common factor in the children’s deaths? They must have, Adelia thought; even the sheriff’s coroner wasn’t entirely stupid. The significance, however, could have escaped them. The Cam was the town’s larder, waterway, and washpot; its banks provided fuel, roofing, and furniture; everybody used it. That all the children had disappeared while in its vicinity was hardly less surprising than if they had not.

But Adelia and Ulf knew something else; Simon had been deliberately drowned in that same water-a coincidence stretched too far.

“Yes, “she said, “it’s the river.”

As evening drew on, the Cam became busy, boats and people outlined against the setting sun so that features were indistinguishable. Those going home after a day’s work in town hailed workers coming back from the field to the south, or cursed as their craft caused a jam. Ducks scattered, swans made a fuss as they took flight. A rowing boat carried a new calf that was to be fed by hand at the fireside.

“Reckon as it took Harold and the others to Wandlebury?” Ulf asked.

“No. There’s nothing there.”

She had begun to discount the hill as the site where the children were murdered; it was too open. The extended suffering they had been subjected to would have required their killer to have more privacy than a hilltop could offer, a chamber, a cellar, somewhere to contain them and their screams. Wandlebury might be lonely, but agony was noisy. Rakshasa would have been fearful of it being heard, unable to take his time.

“No,” she said again. “He may take the bodies to it, but there’s somewhere else…” She was going to say “where they’re put to death,” then stopped; Ulf was only a little boy, after all. “And you’re right,” she told him. “It’s on or near the river.”

They continued to watch the moving frieze of figures and boats.

Here came three fowlers, their punt low in the water from its piles of geese and duck destined for the sheriff’s table. There went the apothecary in his coracle-Ulf said he had a lady friend near Seven Acres. A performing bear sat in a stern while his master rowed it to their hovel near Hauxton. Market women went by with their empty crates, poling easily. An eight-oared barge towed another behind it bearing chalk and marl, heading for the castle.

“Why d’you go, Hal?” Ulf was muttering. “Who was it?”

Adelia was thinking the same thing. Why had any of the children gone? Who was it on that river had whistled them to the lure? Who had said, “Come with me?” and they’d gone. It couldn’t have been merely the temptation of jujubes; there must have been authority, trust, familiarity.

Adelia sat up as a cowled figure punted past. “Who’s that?”

Ulf peered through the fading light. “Him? That’s old Brother Gil.”

Brother Gilbert, eh? “Where’s he going?”

“Taking the host to the hermits. Barnwell’s got hermits, same as the nuns, and near all of ’em live along the banks upriver in the forests.” Ulf spat. “Gran don’t hold with them. Dirty old scarecrows, she reckon, cuttin’ theyselves off from everybody else. Ain’t Christian, Gran says.”

So Barnwell’s monks used the river to supply the recluses just as the nuns did.

“But it’s evening,” Adelia said. “Why do they go so late? Brother Gilbert won’t be back in time for Compline.”

The religious lived by the tolling of holy hours. For Cambridge generally, the bells acted as a daytime clock; appointments were made by them, sandglasses turned, business begun and closed; they rang laborers to their fields at Lauds, sent them home at vespers. But their clanging by night allowed sleeping laity the schadenfreude of staying in bed while nuns and monks were having to issue from their cells and dorters to sing vigils.

An appalling knowingness spread over Ulf’s unlovely little features. “That’s why,” he said. “Gives ’em a night off. Good night’s sleep under the stars, bit of hunting or fishing next day, visit a pal, maybe, they all do it. ’Course the nuns take advantage, Gran says, nobody don’t know what they get up to in them forests. But…”

Suddenly, he was squinting at her. “Brother Gilbert?”

She squinted back, nodding. “He could be.” How vulnerable children were, she thought. If Ulf with all his mother-wit and knowledge of the circumstances was slow to suspect someone of standing that he knew, the others had been easy prey.