As the plot slowly unfurls, it's not known where in the world King Abdullah is (and he's glimpsed in Yemen, Bahrain, Riyadh), but he definitely isn't in his Economic City. Waiting not so much for Godot as his Royal Highness, Alan passes the time in reality and his own head: his day-to-day present in KAEC mingles with his past in America.

Apart from his daughter's future, he muses on his unstable ex-wife, Ruby, his next-door neighbour (Charlie Fallon), who drowned in the lake outside their homes, his inability to sell said house to alleviate his desperate financial situation, his ailing business career (he helped bring down an American manufacturing institution, bike-makers Schwinn) and the disappointment of his union-evangelising father, Ron.

Alan's day-to-day life progresses through slight variations that slowly accrue towards a kind of existence. He fusses over a lump in the back of the neck, graduating from obsession to attempted self-surgery with a serrated knife. This reckless act was attempted while drinking powerful, illicit alcohol, supplied by an attractive Danish consultant called Hanne who also introduces Alan to the epicurean expat night life.

Alan is curiously unaffected by even Hanne's unmistakable advances. Instead, he throws his lacklustre energies into anticipating the life-altering meeting with the king and writing a letter to Kit, explaining himself, his ex-wife and their ill-fated marriage.

As that title suggests, insubstantiality and its opposites (variously: reality, materiality, values, morality, faith, belief) are Eggers' grand themes. This takes in everything from the West's love affair with illusory credit to the outsourcing of its manufacturing base; from Reliant's virtual techno-wizardry to the hopes and fears for King Abdullah Economic City itself (a model city that exists only as an impressive set of models); from Alan's strange dreams about marriage, family and career to the vision of himself (younger, wealthier and, in one reminiscence, elegant) that haunts his waking moments.

All this is summed up in King Abdullah's royal personage which exists as much as an idea as a corporeal presence. In Eggers' nightmarish fictional universe, the long-awaited monarch is an emblem of perfection in a fallen world. Of course the king is only perfect because, for most of the novel, he exists only in theory, as a promise, tease and panacea for all of Alan's - and by extension - the universe's problems. Abdullah's power in absentia also underlines the United States' relative decline in a new world order dominated by Middle East oil money and Asian labour. The ironies inherent in this change are beautifully described in one of Alan's reveries.

A former colleague, Terry, wins a lucrative contract to supply blast-proof windows to the Freedom Tower being built on the site of the World Trade Centre. Terry loses the contract only to find it has been awarded to a rival firm. His devastation deepens when he learns this firm is sub-contracting their construction to another company in Las Vegas. This company in turn is sub-contracting to a company in China which is using a patent owned by Terry's company to make the windows at the lowest price.

And so the circle is completed, leaving the American dream out in the cold.

This elegant parable is typical of the way Eggers elevates Alan's existence, which is narrated with simple language and hypnotic rhythms from the banal to the existential: "There had to be some reason Alan was here. Why was he in a tent a hundred miles from Jeddah, but also why was he alive on earth? Very often the meaning was obscured. Very often it required some digging. The meaning of his life was an elusive seam of water hundreds of feet below the surface, and he would periodically drop a bucket down the well, bring it up and drink from it. But this did not sustain him for long."

Alan is a hapless and oddly compelling protagonist. He is a fool as more than one character labels him, but his foolishness is endearing and even profound. Wandering the desert in his all-American khakis, one hears faint echoes of King Lear and his entourage navigating a different but similarly blasted landscape. One could also point to Alan's charming ability to remember jokes (which he can recite for two hours straight without repetition). This wins the respect and affection of Yousef, who begins as Alan's accidental chauffeur and graduates to his only friend.

Like the sojourn in the unreal KAEC, this short-lived relationship proves more substantial than almost any other in Alan's existence. It is a fiction, but as any great novel illustrates, fiction can be weightier and more powerful than real life (whatever that is).

is a great novel in an unassuming, Alan Clay sort of fashion. Funny, entertaining, subtle, and simple in its prose and execution, it feels like a slip of a story. Yet as Eggers shuffles his central motifs, characters and scenarios, it attains an emotional and intellectual weight that's unmatched by many American novels of recent years.

This is a novel about shallowness and the everyday that sees far beyond the limitations of its subject. It is also great fun, deeply sad and profoundly affecting. is - no joke intended - the real deal.