Second volume in the Isis trilogy. In this, the third generation of children have been born and a rigid, taboo bound society has developed in the colony that was established in the first volume. Survivors of the original colonists are labelled 'Firsts', their children 'Seconds' and so on down to 'Fourths'.

Jody is the youngest Third and finds himself a misfit, partly because of the enmity between his grandfather of the same name, who was rescued by the Keeper of the Isis Light, Olwen, in the first volume, and Mark London, Olwen's lost love who has become the President. Mark presides over a primitive society that he has deliberately made so, cutting them off from knowledge of who they really are and from technology, so that when Olwen's Guardian robot supplies 'gifts' over the years to fix things that don't work any more, such as the communication device, they are totally ignorant of the purposes of such things and instead revere them as artefacts only viewable by the favoured few. They now believe the Guardian is a god - pretty ironic when the first book showed how the colonists looked down on him as a robot - and London's machinations have worked so well that Fourths now don't even believe that the colony came from Earth, and think the stars are just decorations in the sky.

The river which once drained through sinkholes and emerged in another valley, has become blocked and the valley is becoming flooded, a serious problem as the rariefied atmosphere of the high passes is almost unbreathable to the humans who have been told not to go to those places anyway by the taboos Mark has created in the wake of his disappointment and anger about Olwen's true nature. Jody tries to alert people to the danger but Mark does everything possible short of murdering the young man, to ensure that his warnings are ignored - pretty illogical but we are meant to feel Mark's pride is too strong for him to unbend even for the survival of his people. It is only when he engineers things so that Jody has to journey out of the valley to seek help from the Guardian, that the young man finally learns the truth.

I wasn't totally convinced that the society would have lost all its knowledge in this time scale. Hughes tries to overcome this by saying that Mark has taught everyone to ignore what the 'elders' say about the old days, and yet he is an elder himself! Also why is Mark not able to e.g. change a lightbulb in the 'Sacred Cave' as they now call the cave housing the computer that was meant to keep them connected with the Guardian (after he and Olwen left at the end of the first book) - Mark could surely make out that he is the only one with a special relationship with the Guardian and therefore able to deal with his gifts. However, he is also supposed to have turned against technology: the only explanation given for this comes later in the story, when Olwen and the Guardian theorise that Mark has turned against technology because it was used by the Guardian when Olwen was a child, giving her various adaptations so that she could survive the thin air in the higher land, and be physically tough enough to be protected from UV and other dangers. Because of the Guardian's mistake in initially giving Olwen an all-enveloping suit to wear, ostensibly to avoid risk of infection from the newly landed colonists but actually to allow them to get to know her before being confronted with her different appearance, Mark fell in love with Olwen - as she did with him - but totally turned against her when he saw her without her suit, unable to see the beauty in her differences.

It is never explained, but presumably the lowly position of women, which Jody wonders about early on in the story, but which is soon dropped as a subject, is another example of Mark's vindictiveness - because a woman 'disappointed' him, he makes the lives of all women a drudgery. I wasn't totally convinced either by the ending - although Jody solves the problem of the flooding, with the Guardian's help, he has to go back and face London and the rest of them, without anything changing for the best in his society. He is also not to tell them that the Guardian fixed it - so how will he be allowed back if he doesn't say that he actually fulfilled the mission he was in effect banished to carry out? ( )