Michelle Paver does a lot of adventurous travel and clearly pays very close attention when she does. The astounding detail is one of the things I appreciate about her children's series, Chronicles of Ancient Darkness, and I appreciate it even more in the two "grown-up" books of hers that I've read. She has a keen eye and is adept not only at putting her observations into words, but also in weaving them into an interesting story. 
 In Thin Air, as in her previous novel, Dark Matter, the darkness, cold, and confusion come through clearly, and in this one Paver adds the breathlessness of altitude sickness, which had me taking deep breaths as I was reading, just to prove that I could. And like with Dark Matter, this novel had me afraid to look over my shoulder after dark. 
 Both are quite good novels, but even though Thin Air is the more recent novel, it has the feel of a warm-up for the tighter and scarier Dark Matter. Both novels are set in the 1930s and peopled with British men intent upon proving something to the world and, even more, to themselves. The characters are distinct, but Paver could almost have put a collection of character traits on separate strips of paper, put them in a hat, and pulled them out, matching them up to names and putting them in both novels in different configurations ("Okay, in this one, one guy will be afraid of dogs, and in the other one, a dog will be afraid of the guy. Now let's draw to see what happens to the medic."). I don't mind that, though. It gives me a chance to see her process as a writer and to feel like I know a little more about how her mind works (I don't really think she draws character traits out of a hat except in the sense that one wears a hat on one's head and I assume she draws the character traits from her head). 
 Even though this one's not my favorite of the two novels, it's still an enjoyable, spooky read. I wish her grown-up books were more easily obtained in the United States...and that there were more of them.