By Vernor Vinge.
I sure am rereading a lot of books lately, aren't I?
I checked this out recently, prompted by A Miracle of Science, and then it sat on my shelf a while because I was reluctant to read it.
Once I started it, it caught me and reminded me how good it was.
In a way, this is a fairly straightforward adventure story. Some kids are lost in a wilderness amidst savage tribes speaking a strange language, and a group of adults sets out on a dangerous voyage to rescue them.
The wilderness, however, is a planet in the Bottom of the Beyond, near the border beyond which faster-than-light travel becomes impossible, and the sophisticated automation that most people are used to falls apart. The rescuers are motivated by a monstrous blight that seems to want to rule the galaxy. Although the children's parents helped create it, those on the rescue mission believe they may have escaped from it with a countermeasure that is the key to its destruction.
Not to mention that the savage tribes are aliens who work best as pack-minds of 4 to 6 individuals each.
I think this is probably a science fiction classic, although some of the sexual innuendos near the beginning are a bit much (they disappear in the second half). Go! Read it! If you like sci-fi, anyway.
And incidentally, I'm left wondering if the author has any relation to Joan Vinge, who is listed in the acknowledgements at the beginning of the book and wrote The Summer Queen. It does seem an unlikely coincidence.