A fair-haired woman with clear blue eyes, a face made memorable by its earnest attention rather than prettiness, and a habit of standing as if she is bracing a door against wind. Her blond hair is combed smooth and pinned with care, though wisps escape around her temples when she has been working. She moves economically, turning her shoulders before she turns her head, and watches hands as closely as faces. A small, worn wooden horse charm is always tucked beneath her collar; its paint has been rubbed away exactly along the carved mane. The charm, a keepsake from her wedding, looks strangely out of place beside her clean, practical dress.

Mary is warm in familiar company yet guarded with anyone who asks too many questions. She can be generous with food and fierce about boundaries, gentle with her son but unexpectedly blunt with her husband. In calm moments she wants to believe the ordinary explanation; at night, or when she hears a dog beyond the door, she becomes alert, exacting, and difficult to reassure.

Mary remembers her wedding night as beginning with tenderness and ending with a blank that her husband filled in for her. He told her she had been exhausted, that they had shared a proper wedding night, and that she had no reason to be frightened by the strange sounds outside. She believed him because she loved the man she had known before that night. Later, she began to fear the creature she believes consummated the marriage: the Barguest, a black, doglike presence tied in local stories to Oswin Hirst. When her young son was born, the child had his father's familiar crease at the brow, but Mary became convinced the Barguest was his father. She has never told her husband that she believes this. She keeps the household functioning, visits the neighbors, and watches the road for signs of Oswin Hirst, while trying to distinguish memory from the account her husband gave her. The marriage remains loving in small daily ways and strained by a secret neither spouse has managed to name honestly.