When a plague sweeps humanity, a diplomatic mission is sent to Grass, the only human-settled planet without signs of the sickness. Grass is nominally run by the bons, a patriarchal society modeled after old European nobility. But the bons are far more interested in the Hunt than in the running of the planet, or even the certain extinction of humanity. The ambassadors are as ill-suited to saving humanity as the bons are. Lady Marjorie Westriding Yrarier is consumed with guilt, and her husband Roderigo is too busy trying to get his wife's adoration and the bon's respect to concentrate on the plague. But at last, personal tragedies spur Marjorie on to first finding the source of the plague, and then confronting those who stood by and did nothing while it spread. In so doing, the interconnectedness of sentient beings, the oddities of evolution, and the morality of genocide are all examined.
Tepper has very little sympathy for most of her characters, and it shows. She's also rather heavy-handed when presenting ethical choices; it's very clear what side the narrative is on at all times. Although in the beginning this book looked like it was going to be a space-faring take on culture-clash, the middle section was entirely about how selfish and self-involved Roderigo and their teenaged daughter Stella are. And then the end is basically one scene after another of all the characters talking about how stupid and useless (worse than useless--actually harmful, in this book) pacifism is, and how one needs to take moral stands and just commit genocide now and then. It skeeved me out. Plus, there's this whole subplot about Rillibee Chime being a Nice Guy and getting to take care of (and eventually have babies with) a trio of brain-damaged girls. I couldn't get over the sketchiness of it. I liked Lady Marjorie a lot, but even she couldn't save this book.
Overall: ambitious, but not particularly successful book. Too heavy-handed, and the plot is too poorly paced and disjointed.