Neal Stephenson's Cryptonomicon is a big book, with a big story to tell. At its heart lies cryptography, that subdivision of mathematics which was intensively researched and developed during the second world war, under the twin spurs of the need for secure military communication in a global conflict and the emerging feasibility of using machines to do calculations. In the post-war era the subject lay dormant (at least in the public imagination) only to be reawakened by the need in today's world for secure communication over the Internet.

The novel's plot cleverly spans these two eras, concentrating on the common thread of machines that compute and people who, fascinated by the philosophical and technical challenge such instruments represent, drive the technology forward. One such person is Randy Waterhouse, who one day casually works out a philosophy of the human condition, including religious belief, based exclusively on those precepts available to a UNIX computer-system administrator! It is therefore entirely appropriate to borrow programming parlance when describing the interlocking plot structure -- it is "nested."

Thus Randy is the grandson of an American mathematical genius who during World War II worked to break the military codes of the Axis powers. You see how it begins to fit, to nest like Russian dolls? There are lots of such clever things in Cryptonomicon. We follow two soldiers, one American and the other Japanese, whose perception of reality has been subtly altered by extreme battle experiences. This distortion gives Stephenson licence when describing the events surrounding them and lends to these sections of the novel, often dealing with violence, a surreal, Ballardesque flavour.

As you might expect from the foregoing, the narrative oscillates between two eras and different characters who, though separated by time, are related by blood and common obsessions (encryption, and then the usual money and sex). In the course of this traverse of time and generations the reader is treated to insightfully chosen episodes in the birth of the digital computer -- for example, Randy's grandfather befriends Alan Turing, the mathematician who theorised on digital computing even before the earliest crude realisations with valve technology. There is also dramatic tension, and lots and lots of humour; the only possible reaction to parts of this book is to laugh out loud.

I've mentioned the obsession with cryptography, so what about money and sex? The money comes in many guises -- from sunken treasure, and secret hoards of gold hidden in the jungle since the war, to money in digital form. In his descriptions of the sex lives of his characters Stephenson ranges from the grand-eloquent to a tone reminiscent of an undergraduate college magazine.

I can understand how someone might dismiss this novel as wordy, unbelievable and meandering. But this would miss the point. Stephenson's use of language throughout the book is impressive, and although the words flow and flow, the novel never loses that indefinable quality of readability. Often the form must be appreciated over the content in that many passages repay re-reading, to be appreciated just for themselves. (I left many hastily requisitioned scraps of paper as bookmarks to aid such revisiting, to the extent that when finished, the book was festooned with assorted scraps of paper, a testament to the treasures to be found between its covers.) Between these same covers stroll many vividly imagined characters, some taken from history, such as General Douglas MacArthur and Reichsmarschall Hermann Goering.

The subject, structure and language of Cryptonomicon give it the capacity to overwhelm, to take ones breath away. My advice: buy it, take a deep breath, read it, finish it. Enjoy.