A book by a doctor who has gone to some extreme places doing medicine (mostly for Americans who venture places they maybe shouldn’t go) talking about how your body does, or does not, deal with extreme conditions. These conditions include on top of Everest, in space, up the Amazon, in a desert, lost at sea, you get the idea. He usually tries to mix firsthand impressions, his own and others', with a medical description of just what is going on inside your body. I enjoyed it. It’s not for everyone. There are some pretty grievous injuries and bad things happen to people and some of them die. But if you’re curious to look into how this stuff works, he’s got a good explanation.