|Vanessa Duncan returns as the skilled amateur detective of Victorian England in this third mystery novel by "Catherine Shaw". (See The Three-Body Problem and Flowers Stained with Moonlight for the earlier two.) This time, the death of a historian with anti-semitic views is the mystery she must solve. Of course, this is the "paradox" of the title since the body was found in a library and the testimony of the witnesses seems to leave no space for a murderer to have been present. (As with the title of the first novel in this series, it is also a "pun" in the sense that it refers additionally to a famous logical paradox concerning a catalog of catalogs.)
Because Vanessa has an interest in mathematics and because her husband is a mathematician (and, more importantly, because "Catherine Shaw" is the pseudonym of a mathematician), the book has some mathematical aspects. In particular, we are introduced to Bertrand Russell, presented as a young (but important) math graduate student who has just worked out his paradox that is to shake the foundations of set theory. Math gets discussed often enough, and with a high level of sophistication...but it is essentially irrelevant to the plot.
So, if this page were not focused on mathematics I probably would barely mention it in the review. I would focus instead on Judaism and anti-semitism, which are the real subjects of the book. The Dreyfus Affair plays a major role in the murder investigation, and the suspects all come from the Hassidic community of London. In fact, Shaw does such an excellent job of presenting Jewish culture that I must presume that she either was raised Jewish herself or put a great deal of research into this aspect of the book. (In particular, there were no "goyishe give-aways", like when James Flint refered to "a payot" in Habitus.)
This book will continue to enthrall those who enjoy the period atmosphere that Shaw creates, presents a solid mystery with a satisfying (if not surprising) resolution, and as an added bonus includes a bit of interesting and accurate information about paradoxes in mathematics. I was also relieved to see that this installation of the Vanessa Duncan mystery series was not presented in the form of letters to her sister. Rather, this reads like an ordinary novel. I found this less distracting, and I generally forgot that Duncan claims to be writing it as a diary for her husband to read.