Infinity's Shore

By David Brin

The second book of the second Uplift Trilogy.

The squatter races of Jijo face more danger as a huge Jophur vessel arrives, searching for the dophin-piloted, Earthling space ship, Streaker. The Jophur entomb the Rothen ship and start interrogating the locals as to the location of the Streaker. The traeki, Asx, is captured by the Jophur and converted to one of them with the application of a master ring and is now known as Ewasx. Ewasx  maintains control over the traeki rings that composed Asx through applications of pain and uses Asx's knowledge of the locals to benefit the Jophur.
Meanwhile the Streaker is still hiding on the ocean floor, trying to remove the heavy crust that enveloped their ship as it passed through the Jijo sun's field. This crust makes the ship too heavy and the crew is trying everything they can think of to remove it.
The group of four youngsters who went forth in a wooden sub to study the ocean floor are rescued by the crew of the Streaker but are held captive, since the Streaker folks don't want the locals to know they are on Jijo.
Meanwhile, back on land, Jijo society is in meltdown and under assault by the Jophur who think they can wring the location the of the Streaker out of the locals. But the fact is that the locals don't know anything about the Streaker. The Jophur think they are being deceptive and punish them by destroying some of their towns, In particular, they go after the g'Kek, who the Jophur obliterated from the known universe and who the Jophur hate even more than they hate Earthlings.
Despite their lack of sophisticated technology, the locals are not going down without a fight and they make some surprising inroads against the Jophur. Meanwhile, on the Streaker, they realize if they don't get off Jijo, then everything the Jijoans have built will be ruined by the Jophur and those who come after them.

This was a pretty good story, lots of stuff going on, lots of action and heroics as the most of the locals band together to stand against the Jophur.  Also interesting was the crew of the Streaker's disbelief that the various races on Jijo could have developed such a peaceful and productive society. Gradually they come to understand how things are and how their presence on Jijo in endangering it all. Sometimes it was hard to keep all the characters straight, with all the story lines to keep in mind, but fortunately the book includes a cast of characters.