I won't say anything further about the plot beyond the Amazon blurb, what with this being a sequel and all. Sometimes a sequel comes along that you're looking forward to so much that it can't possibly meet your expectations. Just occasionally one comes along that defies your expectations. The Coldest War completely floored me. With it, Tregillis has not only refined his writing skills, he has also excised the aspects of Bitter Seeds that maybe didn't work so well, taken the parts that did work, and kicked them up several levels.
Take the first book as set-up. Now he is polishing and honing his ideas until they are dazzling. Every question left unanswered at the end of the first book is answered here, revelations that - on a couple of occasions - had my jaw hanging open in awe. I could actually feel my heart thumping as I read the final chapters. I had no clue what was going to happen and, when it did, I immediately read it again, then dived back into the first book to look for something, and then felt my jaw hanging open again.
One thing I can say, without really spoiling anything, is that the action - with the exception of a handful of stunning set-pieces - is actually played down in this book. The emphasis is very much on the characters, and the effects the events in the first book has had on their friendships, their marriages, their families. The science fiction elements are still there, woven seamlessly into the telling of the story. Tregillis has a set of rules and he sticks to them - the Lovecraftian horror and man-made super-humans serve the story, rather than vice versa - but oh how they serve it. Gretel is still the character who stands head and shoulders above the rest, enigmatic, scary, charming, with everyone being aware that they are being manipulated, but nobody quite sure how or why.
On the cover of each of these books is a quote from George RR Martin saying that Tregillis is 'A major talent'. Now George and Ian are friends, apparently, so I would normally take that with a pinch of salt, but I think I might have to agree with him. This is only Tregillis's second book. I can't wait to see what happens next, and what he does beyond that.