Whichever one it was had swooped through her solar window last night in the shape of a magpie. It carried a living child in its claws. Sitting on Adelia’s chest, it dismembered the body, a lidless eye gleaming perkily at her as it pecked out the child’s liver.

It was a visitation so vivid that she woke up gasping, convinced a bird had killed the children.

“Where is Master Simon?” she asked Gyltha. It was early; the west-facing windows of the hall gave onto a meadow that was still shadowed by the house until its decline approached the river, where sunlight was shining on a Cam so polished, so deep and flat and wandering among the willows that Adelia had to suppress a sudden urge to go and dabble in it like a duck.

“Gone out. Wanted to know where there was wool merchants.”

Irritably, Adelia said, “We were to go to Wandlebury Hill today.” It had been agreed last night that their priority was to discover the killer’s lair.

“So he did say, but acause Master Darkie can’t go, too, he are going termorrer.”

“Mansur,” Adelia snapped. “His name’s Mansur. Why can’t he go?”

Gyltha beckoned her to the end of the hall and into Old Benjamin’s shop. “Acause of them.”

Standing on tiptoe, Adelia looked through one of the arrow slits.

A crowd of people was by the gate, some of them sitting as if they had been there a long time.

“Waiting to see Dr. Mansur,” Gyltha said with emphasis. “’S why you can’t go pimbling off to the hills.”

Here was a complication. They should have foreseen it but, in allowing Mansur to be set up as a doctor, an untried, foreign doctor in a busy town, it had not occurred to them that he would be burdened with patients. News of their encounter with the prior had spread; a cure for ills was to be found in Jesus Lane.

Adelia was dismayed. “But how can I treat them?”

Gyltha shrugged. “From the look, most of ’em’s dying anyway. Reckon as them’s Little Saint Peter’s failures.”

Little Saint Peter, the small, miraculous skeleton whose bones the prioress had trumpeted like a fairground barker all the way from Canterbury.

Adelia sighed for him, for the desperation that sent the suffering people to him, and, now, the disappointment that brought them to her. The truth was that, except in a few cases, she could do no better. Herbs, leeches, potions, even belief could not hold back the tide of disease to which most of humanity was subject. She wished it wasn’t so. God, she wished it.

It was a long time, in any case, that she’d had to do with living patients-other than those in extremis when no ordinary doctor was available, as the prior had been.

However, pain had gathered outside her door; she could not ignore it; something had to be done. Yet if she were to be seen practicing medicine, every doctor in Cambridge would go running to his bishop. The Church had never approved of human interference in disease, having held for centuries that prayer and holy relics were God’s method of healing and anything else was satanic. It allowed treatment to be carried out in the monasteries and, perforce, tolerated lay doctors as long as they did not overstep the mark, but women, being intrinsically sinful, were necessarily banned except in the case of authenticated midwives-and they had to take care not to be accused of witchcraft.

Even in Salerno, that most esteemed center of medicine, the Church had tried to enforce its rule that physicians should be celibate. It had failed, as it had failed in prohibiting the city’s women practitioners. But that was Salerno, the exception which proved the rule…

“What are we to do?” she said. Margaret, most practical of women, would have known. There’s ways round everything. Just you leave it to old Margaret.

Gyltha tutted. “What you whinnicking for? ’S easy as kiss me hand. You act like you’m the doctor’s assistant, his potions mixer or summat. They tell you in good English what’s up with they. You say it to the doctor in that gobble you talk, he gobbles back, and you tell ’em what to do.”

Crudely put but with a fine simplicity. If treatment were needed, it could appear that Dr. Mansur was instructing his assistant. Adelia said, “That’s rather clever.”

Gyltha shrugged. “Should keep us out the nettles.”

Told of the situation, Mansur took it calmly, as he took everything. Gyltha, however, was dissatisfied with his appearance. “Dr. Braose, him over by the market, he’s got a cloak with stars on it, and a skull on his table and a thing for telling the stars.”

Adelia stiffened, as she did at any suggestion of magic. “This one is practicing medicine, not wizardry.” Cambridge would have to settle for a kaffiyeh framing a face like a dark eagle and a voice in the upper ranges. Magic enough for anybody.

Ulf was sent to the apothecaries with a list of requirements. A waiting area was established in the room that had been the pawnshop.

The very rich employed their own doctors; the very poor treated themselves. Those who’d come to Jesus Lane were neither one nor the other: artisans, wage earners who, if the worst came to the worst, could spare a coin or two, even a chicken, to pay for treatment.

The worst had come to most of them; home remedies hadn’t worked, nor had giving their money and poultry to Saint Radegund’s convent. As Gyltha had said, these were Little Saint Peter’s failures.

“How did this come about?” Adelia asked a blacksmith’s wife, gently swabbing eyes gummed tight with yellow encrustation. She remembered to add, “The doctor wants to know.”

It appeared that the woman had been urged by the prioress of Saint Radegund’s to dip a cloth into the ooze of decomposing flesh that had been the body of Little Saint Peter after it was dragged from the river, then wipe her eyes with it in order to cure her increasing blindness.

“Somebody should kill that prioress,” Adelia said to Mansur in Arabic.

The blacksmith’s wife caught the meaning, if not the words, and was defensive. “Weren’t Little Saint Peter’s fault. Prioress said as I didn’t pray hard enough.”

“I’ll kill her,” Adelia said. She could do nothing about the woman’s blindness but sent her on her way with an eyewash of weak, strained agrimony that, with regular use, should get rid of the inflammation.

The rest of the morning did little to alleviate Adelia’s anger. Broken bones had been left too long and set crookedly. A baby, dead in its mother’s arms, could have been saved its convulsions by a decoction of willow bark. Three crushed toes had gone gangrenous-a cloth soaked in opium held for half a minute over the young man’s nose and swift application of the knife saved the foot, but amputation would not have been necessary if the patient hadn’t wasted time appealing to Little Saint Peter.

By the time the amputee had been stitched, bound, rested, and taken home, and the waiting room emptied, Adelia was raving. “God-damn Saint Radegund’s and all its bones. Did you see the baby? Did you see it?” In her temper, she turned on Mansur. “And what were you doing, recommending sugar for that child with the cough?”

Mansur had tasted power; he’d begun to make cabalistic arm movements over the patients’ heads as they bowed before him. He faced Adelia. “Sugar for a cough,” he said.

“Are you the doctor now? Sugar may be the Arab remedy, but it is not grown in this country and is very expensive here; neither, in this case, would it be any damned use.”

She stamped off to the kitchen to take a drink from the bouser, flinging the tin cup back into the water when she’d finished. “Blast them, blast their ignorance.”

Gyltha looked up from rolling pastry crust; she’d been on hand to interpret some of the more impenetrably East Anglian symptoms-“wambly” had proved to mean unsteadiness of the legs. “You saved young Coker’s foot for un, though, bor.”

“He’s a thatcher,” Adelia said. “How can he climb ladders with only two toes on one foot?”