There remained the mystery of why the King of Sicily should involve Simon of Naples, one of his most capable investigators, let alone herself, in a predicament that the Jews of a wet, cold little island on the edge of the world had gotten themselves into. Simon had not known, nor had she. Their instructions were to see the Jews’ name washed of the taint of murder, an aim to be accomplished only by discovering the identity of the true killer.

What she had known was that she would not like England -and she didn’t. In Salerno, she was a respected member of a highly regarded medical school where nobody, except newcomers, expressed surprise on meeting a female practitioner. Here, they’d duck her in a pond. The bodies she’d just examined had darkened Cambridge for her; she’d seen the results of murder before but rarely any so terrible as these. Somewhere in this county a butcher of children walked and breathed.

Identifying him would be made harder by her unofficial position and the pretense that she wasn’t doing it at all. In Salerno she worked, however unacknowledged, with the authorities; here she had only the prior on her side, and even he dare not declare the fact.

Still resentful, she went to sleep and dreamed dark dreams.

SHE SLEPT LATE, a concession not usually granted to other guests. “Prior said as you could forgo matins, you being so tired,” Brother Swithin, the chubby little guest-master told her, “but I was to see you ate hearty when you woke.”

She breakfasted in the kitchen on ham, a rare luxury for one who traveled with a Jew and a Moslem, cheese from the priory’s sheep, bread fresh from the priory’s bakery, new-churned butter and preserve of Brother Swithin’s own pickling, a slice of eel pie, and milk warm from the cow.

“You was thrawn, maid,” Brother Swithin said, ladling her more milk from the churn. “Better now?”

She smiled at him through a white mustache. “Much.” She had been thrawn, whatever that was, but vigor had returned, resentment and self-pity gone. What did it matter that she must work in a foreign land? Children were universal; they inhabited a state superseding nationality with a right to protection by an eternal law. The savagery inflicted on Mary, Harold, and Ulric offended no less because they were not Salerno-born. They were everybody’s children; they were hers.

Adelia felt a determination such as she had never known. The world had to be made cleaner by the removal of the killer. “Whoso shall offend one of these little ones, it were better for him that a millstone were hanged about his neck…”

Now, round the neck of this offender, though he was as yet in ignorance of it, had been hung Adelia, Medica Trotula of Salerno, doctor to the dead, who would strive with all her knowledge and skill to bring him down.

She returned to her cell to transcribe her observations from slate to paper so that, on her return to Salerno, she might deliver a record of her findings-though what the King of Sicily wanted with it, she did not know.

It was terrible work, and slow; more than once she had to throw down her quill in order to cover her ears. The walls of the cell echoed with the children’s screams. Be quiet, oh, be quiet, so that I may track him down. But they had not wanted to die and could not be hushed.

Simon and Mansur had already departed to take up residence in accommodation the prior had found for them in the town so that the mission might have privacy. It was gone noon before Adelia set off after them.

Believing it to be her business to investigate the murderer’s territory and see something of the town, she was surprised, but not displeased, to find that Brother Swithin, busy with a new influx of travelers, was prepared to let her go without an escort and that in Cambridge’s teeming streets, women of all castes bustled about their business unaccompanied and with faces unveiled.

This was a different world. Only the students from the School of Pythagoras, red-capped and noisy, were familiar to her; students were the same the world over.

In Salerno, thoroughfares were shadowed by upper walkways and overhangs built to keep out a barbarous sun. This town opened itself wide like a flat flower to catch what light the English sky gave it.

True, there were sinister side alleys with tweedy, reed-thatched houses crammed together like fungi, but Adelia kept to main roads, asking her way without fear for her reputation or purse as she would not have done at home.

Here it was water, not sun, that the town bowed to; it coursed in runnels down both sides of a street so that every dwelling, every shop, had a footbridge to it. Cisterns, troughs, ponds confused the sight into seeing double; a roadside pig was exactly reflected by the puddle it stood in. Swans apparently floated on themselves. Ducks on a pond swam over the arched, chevroned doorway of the church looming above it. Errant streams contained images of roofs and windows, and willow fronds appeared to grow upward from the rivulets that mirrored them.

Adelia was aware that Cambridge piped to her, but she would not dance. To her, the double reflection of everything was symptomatic of a deeper duplicity, two-faced, a Janus town, where a creature that killed children walked on two legs like any other man. Until it was discovered, all of Cambridge wore a mask that she could not look on without wondering if a wolf’s muzzle lay beneath.

Inevitably, she lost her way.

“Can you direct me to Old Benjamin’s house, if you please?”

“What you want with that, then, maid?”

This was the third person she’d stopped with a request for direction and the third to inquire why she wanted it. “I’m considering opening a bawdy house” was an answer that came to mind, but she’d already learned that Cambridge inquisitiveness needed no tweaking; she merely said, “I should like to know where it is.”

“Up the road a ways, turn left onto Jesus Lane, corner facing the river.”

Turning to the river, she found a small crowd had gathered in order to watch Mansur unpack the last contents of the cart, ready to carry them up a flight of steps to the front door.

Prior Geoffrey had considered it only just, since the three were here on the Jews’ behalf, that the Salernitans should occupy one of Jewry’s abandoned houses during their stay.

He’d considered that to move them into Chaim’s rich mansion a little farther along the river would be ill-advised.

“But Old Benjamin has inspired less animosity in the town, for all he’s a pawnbroker, than did poor Chaim with his riches,” he’d said, “and he has a good view of the river.”

That there was an area called Jewry, of which this place stood on the edge, brought home to Adelia how the Jews of Cambridge had been excluded from or had excluded themselves from the life of the town-as they had been from nearly all the English towns she’d passed through on the way.

However privileged, this was a ghetto, now deserted. Old Benjamin’s house spoke of an incipient fear. It stood gable end on the alley to present as little of itself as possible to outside attack. It was built of stone rather than wattle and daub, with a door capable of withstanding a battering ram. The niche on one of the doorposts was empty, showing that the case holding the mezuzah had been torn out.

A woman had appeared at the top of the steps to help Mansur with their luggage. As Adelia approached, an onlooker called, “You doing for they now, then, Gyltha?”

“My bloody business,” the woman on the steps called back. “You mind yours.”

The crowd tittered but did not move away, discussing the situation in uninhibited East Anglian English. Already, something of what had happened to the prior on the road had become common currency.

“Not Jews, then. Our Gyltha wouldn’t hold with doing for the ungodly.”