Bruno Cadogan is writing a dissertation on Borges' view of the tango--especially the older, less sentimental tangos Borges would have heard in his youth--when he hears that in Buenos Aires there is a man, Julio Martel, who sings the tango in this older style. Since no recordings exist of Martel's singing, Bruno heads to Buenos Aires to seek him out personally.
When he lands in Buenos Aires, he finds a room for rent in the very same building which housed Borges' Aleph in the story of the same name. From here he begins his quest for Martel, which turns into a labrynthine wandering through Buenos Aires in time and space. Martel, it turns out, has decided to forgo a career in order to use his tango singing to mark off places and events in the city that hold some particular meaning for him. He also becomes fascinated by the possibility of finding the Aleph in the house where he is staying.
This labrynthine wandering was the strongest aspect of the novel, and I really appreciated how Martinez explored and even celebrated the city of Buenos Aires and its lengthy and often tragic history. I cannot say if someone who has never visited the city would feel something similar, but I would certainly hope that the book would provide some motivation for planning a visit.
The novel did have a couple of flaws. Bruno Cadogan is meant to be an American, but he really thinks and acts more like an Argentine. While a minor flaw, it does cost the novel some verisimilitude. For me the larger flaw was that the novel was almost too Borgesian (never did I thought I would say that) in its use of allusions and homages to the point where it almost became distracting. (Bruno himself seems an obvious homage to Cortazar's "The Pursuer," also about a writer named Bruno fascinated with a troubled musician whose art allows him to experience time differently.)
Despite these flaws, I still found it a captivating read and greatly enjoyed its wanderings through the mazes of space and time which make up the reality of Buenos Aires.