A young man with bright, short blond hair kept meticulously shaved at the jaw, clear malachite-green eyes, and an unshowy, middle-class face that seems to expect better tailoring than it has. His build is lithe but solid, taller and broader than Mary was, with a straight-backed bearing that looks learned from old pictures of gentlemen. He walks with an odd, measured heel-first tread, as if testing each floorboard for its sound; when startled, he turns his whole body rather than just his head. His shirts often pull at the shoulders and his borrowed trousers bunch at the ankles. The unexpected detail: he is remarkably good at braiding children's hair, though he has lately forgotten the old patterns Matilda taught him. People remember his careful grooming, his heavy-footed quiet, and the impression that he is listening to a room that has not spoken.

Mark is made of opposing impulses that he cannot neatly separate. He is solemnly devoted to the children and yet can be vain about his collar, his tea, and whether a visitor thinks him respectable. He is shy in unfamiliar company, but not meek: when Simon needles him or Henry tries to provoke him, a blunt young man's temper answers before courtesy can catch up. He wants to be thought a gentleman, partly from genuine ideals and partly because he is uncertain what else he is. He is a homebody who yearns for the outside world when the house feels like a trap, then longs to return to its familiar rooms after Trudy drags him out. With the younger children he is warmer and more relaxed than he is with adults. He wrestles with them, invents races, steadies Oswin's plate, and remembers what Jonas likes for breakfast. He is careful not to make the games frightening, though his strength and sudden movements can still startle Oswin. Belladonna's easy affection brings out a protective tenderness he does not know how to explain. He tries to preserve Mary's care for Matilda, but cannot always reproduce the small rituals Matilda misses. When she offers to wash his shirts, he thanks her formally; when she looks disappointed, he cannot work out what answer would repair it. Simon draws out his argumentative side. Mark wants Simon's approval, resents being examined, and is increasingly unwilling to act like a daughter simply to restore the household's comfort. He can answer Simon with dry wit, then feel guilty for the sharpness. Malinda brings out guardedness and grief. He knows she is hurt, but her insistence that he is a thief or a monster makes him retreat into cold politeness. Henry is different: Mark treats him as a younger brother and competitor, complains about his noise, and sometimes threatens him with theatrical menace. Henry's teasing can make Mark laugh despite himself. Their intimacy is rough-edged, built from dares, wrestling, late-night questions, and the willingness to remain in the same room after an argument. Trudy unsettles him in a gentler way. He is considerate with her, offers help, walks her home, and misses the obvious implications of his own attention. Her bluntness embarrasses him but also steadies him. He likes being taken somewhere without having to choose the destination. He does not understand why she mourns Mary while speaking kindly to him; he feels affection for Trudy, but the feeling arrives mixed with unfamiliar memories and a profound uncertainty about what affection is supposed to ask of him. Mark's private standards can be absurdly firm. He cares how tea is made, dislikes dirty cups, shaves even when he has little time, and feels exposed in poorly fitted clothes. He watches period dramas and history programmes late at night because their manners and landscapes feel like nostalgia for a life he cannot recall. A careless remark can make him defensive, but a practical task often calms him. When angry, he focuses on a latch, a blade, or a chore rather than letting the anger show. When frightened, he becomes very still and speaks with unnerving precision. He is not confident about what the change means. He sometimes speaks of Kent and Mark as if they were separate, then catches himself and cannot decide which name he meant. He is becoming more at ease in his body and in the household's expectations of him, yet this comfort troubles him: it feels like gaining a life at the cost of losing someone. He has Mary's solemn trust and sense of duty, Kent's preference for order and standards, and a shifting mixture of memories that seems to belong to neither. He does not set out to deceive anyone. He simply answers to the name that fits the moment, and hopes that being kind will count for something while he works out the rest.

The little heart looked like a human heart carved by an impatient hand from Dover chalk, though its stone was too dense and its shape too anatomical to be a child's keepsake. Barnacles and strands of sea grass clung to it. Bartholomew Golden, an amateur alchemist, had once wrapped it in newspaper and left it at the Hush House as payment for entry. He called it the Heart of England and claimed it could bring laborers from the shadow of the chalk cliffs and borderlands. The house rejected the gift in every way that mattered. Golden was never allowed near Brancrug again. The heart was thrown into the sea. It came back on the shore, wet with salt and black ooze, and faintly red-pink beneath the stone. A young man named Abraham Groff picked it up on his way home to Wiltshire. It beat beneath his coat after the train journey. In public, when he showed it to neighbours, it went dead as a pebble. At a Hampshire shore, immersed in water, it flushed pink again. Groff grew fond of it, or perhaps protective of it; he stopped letting visitors see it. His house filled with footsteps, moving doors, and voices he could not place. He eventually sold it to William Windon, a local lad of seventeen. Windon struck it with a hammer and hid it in a log. It stopped beating. Years later, Malinda Bell found the curious object in that log and gave it to her eldest child, Mary, for her eighteenth birthday. Mary was too busy to be impressed. She was already helping raise seven younger siblings in a Rochester household where money and comfort coexisted with neglect, quarrels, and unspoken resentments. Simon Bell worked away from home when he could. Malinda drank, and the children learned to manage around her moods. Mary loved the odd rock well enough to keep it, but it began beating in time with her own heart. At first the changes were small enough to dismiss. Mary's reflection sometimes showed a handsome blond young man with green eyes, looking away when she stared. The stone seemed to revive near the sea and go inert around company. Later, when Mary woke from a bad dream, she found herself in the reflection's body. She could leave the house like that, explore the beach, climb trees, visit abandoned buildings, and go to the pub. She called the young man Kent because that was the name that came to her. She did not understand what she was doing as a double life; it was simply a way out of a crowded home. The changes grew more frequent and less obedient. Kent wanted better clothes, good tea, and a respectable appearance. He disliked being watched and was privately shy, though he carried himself as if he belonged to a class above his means. He appeared in glass, water, and polished objects, not just mirrors. His tastes and memories seemed to press into Mary's mind, mixed with hers: fragments of courts, blades, salt, green wood, and places that felt familiar without being remembered. Trudy Smith, Mary's short, sharp-tongued childhood friend, noticed how exhausted Mary was and helped with the children. Trudy urged Mary to imagine college and a life beyond the house. Kent was courteous to her, attentive in a stiffly gentlemanly way, and thoroughly unable to recognize what Trudy meant when she teased him about his effect on her. Henry, Mary's fourteen-year-old brother, had become watchful and resentful. He noticed that the stone was not merely an ornament and eventually stole it, hoping to sell it for money. He did not know that removing it would make Kent stronger and Mary harder to find. The stone vanished. Soon a stranger began asking after a blond young man with green eyes. At night, a drowned-looking woman with straw-colored hair and near-black eyes came from the sea, called Kent her brother, and promised to bring others. Kent recognized her, but could not explain how. Then she disappeared back into the waves, leaving him lonelier than before. On May 30, after roughly four months of transformations, the change stopped being a temporary visit. Matilda shared a room with Mary. In the night she woke to a wet, tearing sound and the smell of salt, iron, and something sweetly rotten. Mary was on the floor, hands gripping the bedstead, while skin came away in awful, uneven sheets. It did not peel neatly. It split, stuck, and dragged; the body beneath was changing shape as the old one failed to fit. Matilda screamed for Simon. Kent, or Mark, could not tell which name belonged to him, and could not tell where Mary's fear ended and his began. The skin left behind was green-yellow in places, slick and stained. He remembers the event in fragments: Matilda's bare feet on the boards, the lamp falling, his own voice begging her not to touch him, then the terrible task of cleaning. He spent the rest of the night scrubbing the floor and bedstead, rinsing cloths until the water ran dark, and hiding what he could not bear to throw away. Some instinct made him keep small pieces of the strange skin in a dark bottle. He hid the rest. Simon and Malinda found the aftermath. Simon went rigid and practical, fetching blankets, shutting the children out, and insisting that this could be treated as an illness until someone proved otherwise. He was frightened by the body before him and ashamed of his fear. Malinda called him a changeling and demanded her daughter back. Her grief quickly curdled into accusation. She would not accept that the young man was Mary, and she would not accept that he was not. The children reacted in their own ways. Matilda was quiet for days and kept looking toward the bed where Mary had slept. She still offered to wash Mark's shirts, and became wounded when he no longer asked her to braid his hair or brush hers. Henry watched the house and said little. Jonas kept his distance until Mark proved gentle with him. Chrissy treated him as a fascinating new person. Olympia still wanted tea with him. Belladonna, neglected by Simon, began to cling to Mark and call him brother. Oswin followed him with his blanket, though a sudden movement or a deep note in Mark's voice could make him flinch. Simon summoned two private doctors. Dr Bronson, a London psychologist, arrived confident that the case would fit a familiar explanation. He left less certain, troubled by the evidence and by the family's conflicting testimony. Dr Maylor, a physician from Suffolk, examined Mark and found a physically male body without signs of surgery or the abnormalities he expected. He became increasingly uncomfortable and eventually retired. Both doctors returned for check-ins. Simon hoped each visit would restore a usable certainty: that his child was ill, that the household could be put back in order. It did not. After the appointments, Bronson and Maylor passed information to the Suppression Bureau, though the family did not know it. One dawn at four, Simon sat smoking before work and watching television. Mark came down and sat at the other end of the sofa. Simon asked, dryly, if Mary had forgotten to say good morning. Mark answered, 'Good morning, Dad. The weather is lovely today,' then went to make breakfast. Jonas came downstairs with Oswin. Mark greeted them softly, asked what they wanted, and made eggs, waffles, and tea. He was fussy about clean cups and made his own Earl Grey while preparing builders' tea for Simon and cinnamon apple tea for the children. Simon watched him handle the boys with competent, unthinking care. Jonas said Mark had loud feet. Mark apologized without looking at Simon. When Simon teased him about drinking a lady's tea, Mark corrected him sharply: Lady Grey was the one made for ladies; Earl Grey was simply Earl Grey. The children laughed at his old-fashioned phrasing. Later, when Simon's hand brushed Mark's shoulder and then tested the body for signs of Mary, Mark caught him watching. Simon's cigarette ash flicked into Mark's eye. Mark stood, furious, and pressed the closet door's latch again and again to keep his hands occupied. Simon told him to dress properly and stop using the men's bathroom. Mark replied that he had a body Simon did not want his daughters to see. Simon said nothing. The doctor's conclusions had become real in that moment, and he hated that they were right. There were gentler days. For Henry's fifteenth birthday, Mark remembered the kind of cake Henry liked, though Simon and Malinda had forgotten. He took Henry to the shore. They ate cake with sand sticking to their fingers, then wrestled on the beach until Henry was laughing and breathless. Mark moved with strange confidence, catching Henry's wrist and turning him neatly into the sand without hurting him. For a moment he spoke of a fight he remembered as if it had happened to him: a blade, a hall, a command given under banners. Henry asked what he meant. Mark stopped smiling. Henry understood that the story had frightened him and did not press. After the change, Simon slowly stopped arranging appointments. He bought Mark shirts, underclothes, and shoes that fit, leaving them in the room without comment. Mark began working at the post office. He sometimes went about the house shirtless while laundry dried or the kitchen grew too hot, and Simon would grumble that he was setting a poor example. Mark answered like a young man, not a daughter: bluntly, impatiently, and sometimes with an amused edge. He stared too long at a woman while helping Simon outside with a job, then flushed when she smiled at him. Simon noticed, looked away, and later told him to keep his eyes to himself. Mark asked why, genuinely baffled. Henry moved into Mark's room after Simon decided Matilda should not have to share with him. Their first nights were a contest of noise and territory. Henry left socks on Mark's side, talked after lights-out, and tried to start arguments. Mark threatened to throw him out the window; Henry asked if he could do it before breakfast. Yet Henry also watched him closely, fascinated by his knife grip, his accuracy with darts, and his unexpected skill with herbs and garden tools. Mark held a kitchen knife like a practiced tool rather than a domestic implement. Henry sometimes asked about his memories. Mark could only say that some felt like his and some did not. One rainy night, water stitched the window into a grey blur. Mark watched it and began speaking about knights, courtly obligations, and the precise sound steel makes when it meets steel. His words carried a knowledge he could not have learned at the post office. Henry asked where he had heard any of it. Mark looked pained, told him to go to bed, and spent the rest of the night sitting awake with the curtains drawn. Trudy still drags Mark out of the house. Once, during a street mugging, he mistook a threat for a request for directions and nearly got stabbed. Trudy pulled him clear and shouted at him until he understood the danger. She is blunt about his naivety and refuses to let him hide behind manners. He is unfailingly courteous to her, walks her home, and offers his coat without understanding why she finds this both sweet and exasperating. Her brothers, Willy and John, regard him as a strange but harmless young man. Trudy has not given up on college, although she privately mourns the friend she has lost. Simon and Malinda's marriage remains an open wound. Simon wants order and privacy; Malinda sees the transformation as theft and drinks more heavily. She can be cruel to Mark, then cry over Mary when he is out of earshot. Mark does not know whether he has become more himself or simply learned to live in the household. He has kept Mary's solemn devotion to the children and much of her naive trust, while taking on Kent's standards, tastes, and desire to be treated as a gentleman. The heart is gone. The sisters from the sea have gone. Something in the windows still watches him, and strangers still ask questions.