Freedom's Challenge: Anne McCaffrey

Book II of The Catteni. The inhabitants of Botany - a mix of humans and extraterrestrials - have built a thriving, productive world from what had been a slave planet. Now they plan to overthrow the terrible Eosi who had existed for centuries by subsuming members of the Catteni race, living in their bodies and ruling pace through them. The Botanists had received unexpected help from the great beings they knew only as the farmers, who had thrown up a huge and impervious space bubble around Botany. Even the Eosi ships could not get through. But the Council knows they must go out and destroy the Eosi on their own ground and vanquish the monster life forms for ever. Cover art y Peter Elson (variation).