PROLOGUE: THE WATER IN MARROW CREEK

The creek had been gray for as long as Tamsin Reed could remember, but on the last night of October it looked like something that had been poured out of a coal scuttle. The fog came down off the ridge in the early evening and settled in the hollow until the chimneys of Marrow Creek poked through it like the masts of drowned ships, and every house in the valley smelled of burning slack and wet wool. Along the bank, where the water slid over the black stones, a thin silver scum had gathered in the eddies, bright as the skin on boiled milk, and Tamsin had learned a long time ago not to look at it for too long.

She was kneeling beside her brother's cot with a basin of lukewarm water between her knees when the coughing started again.

It began the way it always did, as a dry catch in the back of Jonah's throat, and then it climbed into something wet and tearing that shook the whole narrow frame of the cot. Tamsin put the basin aside and pulled him upright against her shoulder. He was thirteen years old and he weighed no more than a sack of seed potatoes, and she could feel every one of his ribs flexing under the flannel of his nightshirt as he fought for air. When the fit finally loosened its grip, he spat into the handkerchief she was holding, and the cloth bloomed red in the lamplight, with a gray cast at the edges that made her stomach turn over.

"I'm sorry," Jonah whispered. "I didn't mean to wake the whole house."

"You haven't woken anyone who wasn't already awake," Tamsin said, and she smoothed the damp hair away from his forehead. "Granny hasn't slept properly since the first frost, and I was only pretending to read."

From the stove on the far side of the room came the sound of a kettle being set down harder than necessary. Granny Odell stood with her back to them, a small, knotted woman in a shawl the color of old oatmeal, stirring a pot of mugwort leaves into water that smelled faintly of green things and vinegar. She had been the healer of Marrow Creek for fifty years, and in all that time Tamsin had never once heard her say that a patient was beyond help, which was why the words she spoke now landed so heavily.

"It's the water," she said, without turning around. "I can brew every leaf on this hillside into a tea and it won't matter, because the minute that boy drinks from the creek, he's swallowing the same poison that's been in this valley since before your mother was born. This creek is killing us, child. It's only doing it slowly enough that nobody in Highmark has to call it murder."

Tamsin did not answer, because there was nothing in that statement she could have argued with. She laid Jonah back against the pillow and drew the quilt up to his chin, and then she took his thin hand between both of hers.

"Hold still for me," she said. "Try to breathe slowly, like we practiced."

"You're not supposed to do that," Jonah said, but he said it without any real conviction, and his fingers curled trustingly around hers.

She shut her eyes and let her attention sink down through her own chest, past her pulse and the tightness in her ribs, to the place where something warm and green had always waited for her. It rose to meet her like a seed breaking its coat. She felt it flow down her arms and into her wrists, and when she opened her eyes the veins beneath the skin had begun to glow a soft, mossy blue-green, bright enough to throw faint branching shadows across the quilt. She laid her free hand flat against Jonah's chest and let the warmth go.

She could feel exactly what was wrong. His lungs were coated in something that clung and burned, a fine gritty film like salt dried onto glass, and her magic moved over it the way a thaw moves over ice, loosening the edges and coaxing the whole stubborn layer to let go. Jonah's breathing deepened. The rattle in his chest dissolved into a long, shaky sigh, and the lines of pain around his mouth smoothed away until he looked like a little boy again.

When she finally pulled her hand back, the room tilted around her. A warm trickle ran over her upper lip, and she wiped it away with her knuckle and found it smeared dark red. Her whole body felt scraped hollow, as though someone had taken a spoon to her and left only the rind.

Granny Odell had crossed the room without a sound and was gripping her shoulder with surprising strength. Her faded eyes darted toward the window, where the fog pressed blankly against the glass. "Tamsin, look at me. You mustn't let anyone see you glow, girl, not the neighbors, not the preacher, and especially not any man in a gray coat with a ledger. Do you understand what I'm telling you?"

"I understand," Tamsin said. "I've understood since I was six years old."

"Then understand it again." Granny dabbed at her nose with the corner of her shawl, more gently than her tone suggested. "That boy is going to need you whole for a good many years yet."

…

The knock came a little before midnight.

It was not the knock of any neighbor, which would have been a rattle of knuckles and a cheerful shout about the fog. These three raps were measured and precise, the kind of knock delivered by someone who had been trained to be patient. Granny's hand went to the poker beside the stove, and Tamsin put herself between the door and Jonah's cot before she even knew she had moved.

The man on the step wore the blue coat and brass buttons of the Imperial Post, and the fog had beaded on his shoulders like frost. He held a leather satchel in one gloved hand and a lantern in the other, and he looked at the crooked cottage, the patched roof, and the girl with the bloodstained lip as though he were reading all of it from a list.

"Miss Tamsin Reed?" he asked. "I was told to deliver this into your hands and no one else's."

The envelope he handed her was thick, cream-colored, and so clean that it made her fingertips look filthy. It was sealed with a disc of white wax, and pressed into the wax was a crest she had only ever seen printed in the newspapers: a tower rising from a cliff with a sunburst behind it, which she knew to be the seal of Vandermere Hall.

She read the letter standing in the doorway while the postman stamped his boots on the step and Granny pretended not to read it over her shoulder. It was written in a clerk's elegant copperplate, and the words were so civil that it took her two readings to find the meaning inside them. Her Imperial Majesty's household required a tutor for the Princess Lila Aldridge, aged eleven. The candidate had been recommended on the strength of her scholarship at Ashby College. The position carried room and board at Vandermere Hall, and a salary of sixty dollars a week.

Sixty dollars a week. Her father had worked the Calder seam for twenty years and had never held sixty dollars at one time in his life. It was more than the whole village of Marrow Creek earned in a month, and for a moment the number swam in front of her eyes like something printed in the wrong language.

"Nobody pays a Hollow girl sixty dollars a week unless they want something from her," Granny said quietly, once the postman had tipped his cap and vanished back into the fog. "You know that as well as I do."

"I know it." Tamsin turned the letter over, as though the back might offer an explanation. "But I also know that Dr. Whitcombe wants forty dollars for a month of the clear tincture, and that I've spent every cent of my scholarship money on the last three bottles, and that the pharmacist in Calder Junction won't extend credit to a Rootkin family at any price."

From the inner room, as if he had been listening, Jonah began to cough again.

It was a small, damp sound, and it went through her like a nail. She stood at the window with the letter in her hand and looked at her reflection in the cracked pane, a thin young woman with brown-red hair coming loose from its ribbon and gray-blue eyes shadowed by exhaustion. On the left side of her neck, just below the jaw, the root-scar showed pale against the lamplight, a branching mark the color of a rose petal, spreading toward her collarbone in fine forking lines like the roots of a plant. She had worn her hair down over it for most of her childhood, and she had stopped doing so the day she left for Ashby, when she decided that she would rather be stared at than be ashamed.

She gathered her hair in both hands, twisted it up, and tied it back with the ribbon so that the scar lay bare.

"Sixty dollars a week," she said again, folding the letter along its creases. "Whatever they want, I expect I can find out what it is before they find out what I am."

"And if you can't?" said Granny.

"Then I'll have been paid in advance for my mistake." Tamsin tucked the letter into her pocket and met her grandmother's eyes. "I'll go to Highmark and find out what they want."

Behind her, in the dark of the little room, Jonah coughed again, and the sound followed her all the way to the door.