I just finished Grass by Sheri S. Tepper.

I read Tepper's True Game series when I was very young - 13 or 14 - and really liked it.  After that series, her books drifted from what I was looking for and I haven't really gone back until now.  I had picked up another book, Sideshow,  but stopped reading it right away when I realized it was actually the third book in a series.  I went back to start with the first book, Grass.

Grass tells the story of the humans who live on a planet covered by plains, and where there is a symbiotic, and not entirely healthy, relationship going on between the humans and the aliens who live there, mainly expressed through a regular "Hunt".  At the same time, humans elsewhere are starting to be effected by a form of plague for which no cure can be found.  The people on Grass seem to be immune, which draws the attention of a the theocratic government that dominates most of humanity.

It's an interesting book, and I look forward to the sequels.