There are four main characters: James, Henrik, Henderson (Alastair) and Alison. They are thrown together by chance and, while passing the island of Jan Mayen in the Arctic, the fog temporarily lifts to reveal a dazzling white volcano; this event seems to bind them together and they make a pact to climb it one day. [The story arose when I once witnessed the volcano do just this.] Perhaps 'reaching the summit' becomes an allegory for much that goes on in the book: Alison cannot finally get together with James until both have achieved something in their lives. But when, at the end of the book, all four do eventually climb the volcano, the summit itself is a disappointment: perhaps better to travel hopefully than to arrive? Although four ascend, only two, Alison and James, return. This then leads to the question, did Henrik (the environmentalist) and Henderson (the businessman) ever exist? Were they real people, or do they represent career paths that James could have taken, or even did take? Or maybe the volcano was never really there? [the answer may be ‘unfathomable’, hence the subtitle of the book.] It is a short book (57,000 words) with little padding, but fast moving with action interspersed with introspection. At one level it is just an adventure story, at another a love story, at another it is about the battle between big business and the environment; at yet another just a description of some parts of the planet we live on, or a critique of leadership, or about how a woman chooses her man, and vice-versa ; about achievement and life's purpose... It follows the lives of the four main characters, mainly from James' perspective (in the first person), but sometimes from Alison's ("I could not understand James..."). It describes some key episodes in their lives, the vignettes including a storm at sea, life as an anti-whaling campaigner, the boardroom of big business, an environmental campaign, a kidnapping where the three men in Alison's life effect a rescue, a love scene, and the final climb of the volcano. The scenes vary from John Buchan-type derring-do to the main love scene, set in the Lake District, when James and Alison finally get together. She has previously found Henderson and Henrik wanting but, ironically, earlier in the story while running away from man trouble finds her true worth as a leader (and finds she cannot avoid men either). Scenes race seamlessly around the world: The Faeroes, Jan Mayen, the High Arctic, the Falkland Islands, the southern ocean, Singapore, The Maldives, The Lake District, Scotland and Iceland.