The time is the present day. Thousands of mysterious glass-like skyscrapers suddenly appear in rural locations all over the world, and a message is sent to world leaders by the aliens who planted them: an offer to fit implants to humans which permit them to be restored after death. Their bodies are delivered to the skyscrapers - Onward Stations - and transmitted in beams of light to an orbiting starship. This takes them to the aliens' home planet - Kéthan - from which, months later, they return in good health, without any previous disabilities; and quite a lot younger if they had been elderly when they died. They can then choose to stay on Earth as "returnees" or accept the aliens' invitation to travel to other worlds to help them with their great civilising mission.
Not surprisingly, this initially results in great suspicion and condemnation from some quarters, especially the world's religions. However, the first returnees prove to be not just as good as new but better; their restoration includes a form of education which turns them into more thoughtful and considerate people, with the usual human personality imperfections smoothed away. As a result, implant wearing becomes the norm, and those who reject it are increasingly regarded as strange.
Kéthani is all about the impact which these developments have on individuals and their attitude to life and death. The focus is on a small group of friends (who gradually change as some drop out and others are added) who regularly meet in a pub in a small Yorkshire village close to one of the Onward Stations. The narrator of the story, one of the group, explains at the start that, many years after the events, he has asked each of his friends to write down their recollections of how they perceived them at the time. The novel is made up of a series of interlinked accounts, with occasional explanatory sections by the narrator, stretching from the time of the aliens' arrival to many years later. They are therefore nearly all written in the first person, only with the viewpoint changing with each chapter (which occasionally requires a small degree of concentration to keep in mind whose viewpoint it is this time).
On the face of it this doesn't sound too promising; there is inevitably some loss of the kind of pace and tension which a good straight-line thriller can provide. However, this is more than compensated for by the way in which we get to know the characters, seeing them from different viewpoints as their lives gradually change over the years. We also see the a wide range of issues and events taking place within the group; couples parting and joining, some dying and some returning. It all adds up to an intriguing picture of the multifarious consequences of the alien intervention.
Much of the book previously appeared in short stories, and this does lead to some discontinuities. For instance, in one episode there is an intervention by a different alien race who are opposed to the Kéthani - but that is the last we hear of them. One obvious consequence of the resurrection process is also left unexplored: what happens to a relationship when one of an elderly couple dies, and returns much younger? A recurring theme later in the book is the gradual depopulation of the Earth as an increasing number of returnees opt to spend their lives on other worlds, but it isn't clear why this should be so. After all, in our pre-Kéthani world they would all have died anyway, yet the world's population continues to rise today since births outnumber deaths; logically, within the twenty-year span of the story, the resurrection process should actually lead to a further increase in population by whatever percentage of the returnees elects to stay on Earth, unless something drastic happens to the birth and/or death rates; but there is no indication of this (at least, not until the end of the book).
Despite these quibbles, this unusual story is an interestingly different take on the well-worn "the aliens have landed" plot.