Nancy Kress continues her space-colonization story with this novel, a sequel to "Crossfire."
In terms of plot, the book opens as the colonists on Greentrees are still caught between the rock of "Furs" and the hard place of "Vines"--alien races at war with each other. The humans are allied with the Vines, who have a plan to eliminate the Fur threat.
If that weren't enough, a ship of humans arrives from Earth, bringing ambitions and prejudices of their own--and a whole new dimension to the conflict.
Without giving away too much, the story unravels a thorny briar patch of conflicts at many levels--among humans, planets, interstellar species, ecologies, technologies, biologies, relativity, and especially philosophies.
It's a massive undertaking on Ms. Kress's part, and she succeeds brilliantly. One of her strengths as a writer is that she has an appreciation for technology without being seduced by it. Better still, she creates very believable characters--the only other writer I can think of who created characters as convincingly was John D. MacDonald. But more than just a character study, she has an intricate, well-paced plot with a resolution that doesn't let anyone off the hook.
Best of all, there's enough threads to support a third entry in the series.