This is a hacker-counter-hacker story set in Bolivia, where the newly resurrected president hires an NSA official to set up the country's counter-espionage / cyber-security unit ("Black Chamber"). The main thorn in the side is a computer terrorist named Kandinski. Black Chamber has on its side a cryptanalyst with decades of experiencing tackling various types of codes. And the game is on, with the inevitable mole inside Black Chamber, fevered dreams which feature the dreamer talking in first person as Charles Babbage, Turing, etc. The book intersperses mathematical references throughout, including a long description of the Enigma machine, Fermat and Mersenne primes, etc. At one point, the Black Chamber director recalls how, as a child, he was taught number theory by his mother using the book, "The Man Who Counted."