A solid book, SF according to the subtitle, but as easily classified as a suspenseful thriller. Very enjoyable and a quick read.
There are three POV characters (not including the -logues), but it’s the two men whose eyes we look out most of the time. They’re smart and driven, each with interesting limitations and blinders. Constance is a very engaging woman– scientist and outdoors woman, with a perfected retreat towards domesticity that comes out a couple of times. The author sells the relationship between the characters; the marriage and unspoken communication are conveyed well.
I’ll probably pick up more of her books at the library soon. (On reading her Wikipedia page, it appears that there are several novels featuring Constance and Charlie– this is the second written.) I also remember her book Where Late the Sweet Birds Sang, an interesting twist on a calm end of the world.