The main setting of the novel is the Central Registry of Births, Marriages and Deaths located in an ambiguous and unnamed city. This municipal archive holds the record cards for all of the residents of the city stretching back endlessly into the past.
The protagonist is named Senhor José; the only character in the novel to be given a proper name (all of the others are referred to simply by some unique and defining characteristic). Senhor José is around fifty years old and has worked as a low-level clerk in the Central Registry for more than two decades. Senhor José's residence, where he lives alone, adjoins the municipal building and contains the only side entrance into it. Lost in the tedium of a bureaucratic job, he starts to collect information about various famous people and decides, one evening, to use the side entrance to sneak in and steal their record cards.
On one nocturnal venture Senhor José grabs the record card of an "unknown woman" by mistake and quickly becomes obsessed with finding her. Senhor José uses his power as a registry clerk to gather information about the "unknown woman" from her past neighbors and, when it is suggested to look her up in a phone book, he ignores the advice, choosing instead to keep his distance.
The search for this woman begins to consume him and affects his work enough so to draw attention from the Registrar — head of the Central Registry— who, strangely, begins to regard Senhor José with sympathy. This special attention given to a clerk by the Registrar is unprecedented in the known history of the Central Registry and begins to worry his fellow employees. Senhor José further neglects his duties as a civil servant and risks his career to pursue this "unknown woman" he knows almost nothing about.
