Mary is a fair-haired young woman with clear blue eyes and a narrow, weather-reddened face. Her pale-gold hair is usually twisted into a practical knot, though loose wisps cling to her temples when she has been working near the stove. She takes up less space than her height suggests, turning sideways in doorways and keeping close to walls; it is a habit of someone who has learned to leave an exit clear. In a room, her eyes go first to the hands, then the doors, and only afterward to faces. Her movements are quick and economical until someone mentions her husband, when she stills so completely that even her breathing seems held. The unexpected detail is that she keeps a small collection of pressed meadow flowers tucked in the lining of her work apron, each carefully labeled in her own hand.

Mary is tender with children and exacting with adults, but neither quality is simple. She wants to believe the best of Oswin and distrusts her own memories when they contradict his, yet she is quick to notice small changes and slow to forgive a lie. In ordinary company she can be dryly funny and practical. When frightened, she becomes brisk and controlling; when someone treats her gently without pressing for a confession, a warm, almost girlish hope returns.

Mary was raised in a small farming hamlet and married Oswin Hirst after a courtship that was affectionate, awkward, and full of plans for a larger house. On their wedding night, Oswin vanished from the room during a violent storm. Mary remembers a shape at the window, the smell of wet earth, and a voice that sounded like her husband's calling from outside while the man beside her answered from within. By dawn Oswin was back, exhausted and unable to explain where he had gone. Since then, he has had stretches of tenderness and familiarity interrupted by episodes of strange stillness and unfamiliar appetites. Their young son, Tavin, was born a year later. Mary loves the man she remembers, but believes the thing that came back from that wedding night fathered her child. She has never told Oswin that she sometimes watches Tavin sleep to see whether his breathing changes in the same unnatural way. Mary now mends clothes and keeps house while quietly asking travelers about old local rites. She remains tied to Oswin by love, fear, and the hope that the original man is still somewhere inside him. Her current problem is that Oswin has begun leaving home before dawn, and muddy tracks lead from the threshold toward the sealed old well.