What an unusual book.
Because it bounces back and forth between times, it's a little hard to follow. But I think the storyline makes the bouncing worthwhile. I am a fan of Gertrude Bell and other early female adventurers, so I am probably a predisposed to like this work.
First, for the 1920s chapters...Ms. Joinson paints the region (then called the Near East) of Russia/China well. Her characters are interesting, although I take exception to Millicent—a total looney—representing Christianity and missionaries. The reader needs to be willing to suspend belief at times, such as regarding the premise that two young women would have been so easily released to undertake a journey of this type at this time.
As to the contemporary part of the story, I think the author does a particularly excellent job of depicting Tayeb. He is believable, based on Westernized, young Middle-Eastern males of his generation. (I know a few.) Her characterization of Frieda is rich, although I'd like to have seen this character exhibit some of the spunk, and less of the politically correct altruism, of Eva.
All in all, this is a very enjoyable read. It's about a region in which I'm interested (both the 1920s chapters, and the contemporary ones), and it well-written. Recommended.