Prime Obsession was published in hardback in April 2003 by Joseph Henry Press of Washington D.C. Various other editions and translations have subsequently been published.
The book is an account, both historical and mathematical, of the Riemann Hypothesis, a famous unsolved problem in mathematics.
Prime Obsession was surprisingly well received for a book of that kind. In January 2007 it was awarded the Euler Book Prize by the Mathematical Association of America. The prize is awarded for the best popular exposition in book form of a mathematical topic.
The great algebraist Jean-Pierre Serre passed some flattering remarks about the book in the course of a lecture he gave as part of the Galois bicentenary celebrations in October 2011. When I first compiled this page there was a video recording of Serre's talk online, but to my great annoyance the link no longer works. All I can now find is a brief text summary of the talk here. If anyone can recover the video, I'd be much obliged. The flattering remarks begin at 20:18. Just to see one's name written up on a blackboard by this great mathematical veteran was incomparably thrilling. Merci, Monsieur.