Many years after the events related in the story, the narrator passes by the house in which he grew up and attempts to reconstruct the circumstances that led to the mysterious disappearance of his aunt Matilde. As a child, he lived in a home that included his widowed father, his unmarried aunt Matilde, and two bachelor uncles, Gustavo and Armando.

Aunt Matilde originally moved into the house in order to take care of the narrator after his mother passed away when he was four years old, but once she settled in, most of her attention went to caring for her own three brothers. Managing the household with a firm and steady hand, Matilde re-created the household in her own image—with more order than warmth, and more impersonal efficiency than human affection.

Surprisingly, one day Matilde took in a stray white dog, which she had found on a street after it was hit by a car. In her devotion to nursing the injured dog back to health, Matilde began to neglect her regular household duties and routines. Gradually the mongrel bitch replaced the brothers as her principal companion. When she stopped joining her brothers for a game of pool every evening in order to take the dog for a walk, it was clear that the life of the family was no longer the same.

This change put Matilde’s brothers in the same situation as the narrator, who had always been neglected by his aunt. It was not in the brothers’ nature to say anything to Aunt Matilde about the disruptive impact of her relationship with the dog. As the narrator remarks, it became “more important than ever not to see, not to see anything at all, not to comment, not to consider oneself alluded to by these events.” Thus, instead of voicing their concerns, they tried to ignore the changes in their lives. As the dog became not just Matilde’s companion but her “accomplice,” Matilde’s walks got longer and longer, and she often came home dirty and disheveled. Finally, one day she went out for a walk and did not return. Although the brothers tried to discover her whereabouts, they had no success. Nevertheless, as the narrator states, “Life went on as if Matilde were still living with us.”