This is the fourth book in Niven's occasional Ringworld series. The first in the series, Ringworld (1970), won him the Hugo and Nebula awards but isn't my favourite of his books, though it's OK.
This one finds him in surprisingly lively mood; he sets about administering various shocks to the system, and finding solutions to the problems that arise, which is clearly what he enjoys doing.
By now, the inhabitants of the Ringworld have to contend not only with their own problems and the problems of the Ringworld itself, but also with the military fleets of various civilizations that have found the Ringworld and see it as a source of valuable information. They're sparring with each other and causing further damage and danger to the Ringworld and its inhabitants.
The situation is a mess to be sorted out by the protector Tunesmith (who came in with the third volume), with some help from Louis Wu and his surviving companions.
It makes a readable and competent sequel. I doubt that Niven's going to win more awards now, but anyone who liked the previous books can confidently buy this one.
My main criticism is that there's only one human female in the book, and I don't like her. Niven has always tended to write about men; he throws in the odd woman from time to time but they don't tend to be very memorable. In the original Ringworld book there was Teela Brown, but she was never much of a character and she died in the second volume.
The title of this book comes about, I suppose, because some of the original explorers who discovered the Ringworld back in the first volume now have children (born on the Ringworld) who are taking part in the story. Though, in fact, they don't have a big contribution to make to it.
The first sentence of the book is, “Louis Wu woke aflame with new life, under a coffin lid.” This is because, at the end of the third volume, he was put into a one-of-a-kind experimental autodoc, which uses nanotechnology to rebuild him cell by cell. Thanks to the use of boosterspice, he was already 243 years old, but injured. Now the experimental autodoc has rebuilt him as a young adult in perfect health.
An autodoc is a machine into which you climb; it then automatically performs whatever surgery and other doctoring it thinks you need. Who would trust such a machine, especially an experimental one? Well, probably anyone who's seriously injured or seriously old. In fact, the crimes some people would commit in order to get into it hardly bear thinking about.
Louis Wu is not only lucky enough to pass through the machine once. At the end of this book, having been seriously injured again, he passes through it again, to emerge just as perfect as he was at the start. Perhaps someday, after I'm dead, such machines will be available and people will take them for granted. Alas! Why was I born in primitive times?
Written in July and August 2009