The book tells two stories in parallel: that of Chia's journey, as she attempts to discover what is going to happen to Rez, her popstar hero, as he has announced his plans to marry an idoru. Rez is half of the band Lo/Rez and has been the biggest thing in pop worship for longer than Chia's life, and yet old as he is he still attracts a youth following. Now even the screaming fans wonder if the choice of a virtual bride does not indicate he is losing something. His idoru is called Rei Toei and she exists only in a computer, though her reality as far as anything can measure it is growing, and people all over Japan know her from her appearances on billboards.
The second story is that of Colin Laney, a data miner, who up until now has used his almost uncanny skills on digging up the dirt on minor celebrities for a sleazeball television programme. Now racked by guilt because his investigations drove a woman to suicide he is being used by the bodyguards of popstar Rez to investigate the world of Rei Toei.
IDORU is a thriller, and though it depends on the forefront of technology for its thesis - all the characters are constantly switiching on computers, accessing data, sending e-mail messages, trying to conflate information - it is not especially technical, and lacks invention in other ways. Love hotels are introduced as a freak, though surely we have all heard of them. In the hotel toilet everything is high-tech, controlled by buttons marked in Japanese, which Chia cannot understand. And the cars on the road are little Japanese runabouts. In fact, Gibson is surprised that Japan is so Japanese - and he keeps pointing out that the writing on things is Japanese, as if the natives as well as Anglo-Saxons should expect everything to be in English.
The question of data mining is much more interesting, and I guess a lot of people would like a job like Colin Laney's. We are all aware of what is involved because the effect of it is being set out in every aspect of our lives. For instance, the loyalty cards issued by supermarkets have an immediate purpose of holding shoppers by offering them discounts, but also allow the buying patterns of individuals to be identified in order to exploit them. If those supermarkets could match their data with that of other commercial organisations, or even government departments, what bigger pictures could they form of their customers?
Gibson's idoru, though, is the opposite. Laney found out more and more about an individual, by putting together the records they had created as they went about their daily life (such as his suicidal woman). Now, if there were records placed in those databases without any one having done anything except insert a record, then a new life would be created. The more records that could be generated in more and more computers would make the reality of that data subject greater all the time. If a computer generated image of her could be built, as well as virtual rooms (or images of real buildings held on a computer) for her to inhabit then the relationship with the world we know would be almost complete. What began during the Second World War with the construction of characters such as Colonel Britton and William Martin (The Man Who Never Was) could reach a new level of influence.
However, rather than investigate these possibilities what Gibson has written is a low key thriller, in which the ultimate cause of the action is a search by Russian gangsters for an item which entered Japan when Chia was stupid enough to carry someone else's luggage through customs. Of course, your analysis of the data may lead you to different conclusions.