The Earth has been brought into the galactic fold, but finds itself a pariah because of its dubious pedigree. All the other races in the galaxy have achieved sentience through uplift by older and wiser species. Or so the galactics' propaganda maintains. Common wisdom dictates that it would be impossible for the upstart human species to discover anything not already in the massive galactic library. But with the prospect of sentient life being discovered on the sun that assumption too may be challenged. When Jacob Demwa is invited to take part in the contact mission, things quickly take a sinister turn.
This book was not what I expected. It's not about uplift in the way I assumed. It is only in retrospect, having read the first two sequels, that I came to appreciate what it is about. Each book focuses on the travails of a sentient species from Earth. It happens to be humans in Sundiver. In the other books, the species in question must deal with issues around its uplift. Humanity in Sundiver faces the skepticism of their newfound allies because there is no evidence that any guiding intelligence was involved in their uplift.
The characters feel a bit flat as does the political background on Earth. There's a lot of clever ideas packed into it, but they're not developed in great detail. On the other hand, the main character Jacob's weird alter ego left me scratching my head. I did enjoy the mystery aspects of it but I preferred the sequels.