Dark Earth by Rebecca Stott (not a review/mostly no spoilers)

I can't remember the last time I actually felt sick with worry about the fate of the characters in a novel. It was such a strong feeling that I almost gave up on the book. I read it in sections over a few evenings to keep my stress levels low instead of bingeing in one night to "get it over with".
That makes it sound like I didn't enjoy the book. Rather, the experience was beyond enjoyment. I'll probably put it in the regular re-read category, although, to make a comparison with A Wizard of Earthsea,( Mild spoiler )