In Banville's 2010 work The Infinities, Adam Godley was a mathematician who worked on theories involving a "multiverse". In this new novel, it is revealed that he proved a theorem on the subject that literally changed the world, allowing for characters from other Banville novels to coexist in this book's reality. For instance, Gabriel Swan from Mefisto (1986) also appears here. In fact, we learn that it is Swan who is responsible for popularizing the term "Brahma Theory" for Godley's universe changing theorem (and for helping to get it published in "Annalen der Mathematik").

The plot (such as it is) mostly follows an academic named Jaybee and a murderer recently released from prison. Jaybee (presumably standing in for the author, J.B. himself) happens to be writing a history book about Godley, and this justifies the pseudo-scholarly style of the novel which includes numerous footnotes. The murderer, also a character from a previous Banville novel, is apparently from another branch of the multiverse. He shows up at Godley's house honestly believing that it is his.

It would be a stretch to say that this book is about mathematics. Rather, it appears to be about our inability to understand the true nature of reality...and an opportunity for Banville to wrap up his oeuvre. But, some characters are mathematicians, and a theorem is used to justify the odd set-up.