Having felt overshadowed by her mathematician older sister when she was alive, the main character becomes obsessed with her murder after the sister is killed. Using her sister's notebook describing her work on many of the famous open problems in mathematics, she learns more about her sister and about mathematics. (Of the open problems mentioned, Goldbach's Conjecture and the question of whether she had proved it before she was killed are of special interest here.)
Math gets mentioned frequently throughout the book, mostly in the form of references to or quotes from the usual crowd of ``famous mathematicians'' (Euclid, Hilbert, Erdös, Ramanujan, Poincare, etc.). Most of these quotes and references are used correctly, but an occasional slipup (e.g. her summary of the Collatz Conjecture as ``A sequence of natural numbers always ends in one'') and the fact that the mathematical content is primarily made up of these quotations from others suggest to me that the author herself is not well versed in mathematics.
If that is the case, then she has really done a surprisingly good job of writing a work of mathematical fiction for a nonmathematical audience. However, anyone with a strong background in mathematics should recognize that they are not likely to see much that they haven't seen before  at least not in terms of the mathematics.
As a novel, on the other hand, this is more of a character study than a murder mystery and is likely to appeal to a wide variety of readers regardless of their mathematical backgrounds.
Contributed by
John C. Konrath
This novel incorporates two of my favorite things, mathematics and coffee. “No One You Know”, tells an elegantly crafted tale that was a pleasure to read. All of the characters are realistic and unique. Overall, this book demonstrates the author’s excellent understanding of human nature.
Mathematically, this work touches on many topics but does not explore any in depth. To a nonmathematician concepts are presented in an interesting manner and can serve as a gateway to further reading.

