As is often the case with Russell books, the mystery feels more like a narrative excuse to explore a subject, place, and time -- in this case the start of the British colonial rule of Palestine, just post-WWI, a fascinating period I knew quite little about, and in which you can see the early seeds for the seemingly intractable conflict there in the present day.

Don't get me wrong, the mystery isn't an afterthought, and I found the subterranean exploration beneath Jerusalem leading up to the denouement fascinating (maybe because I've always enjoyed doing that sort of thing). But Mary's sojourn in disguise as a young man, learning the culture and language and how to win over her prejudiced companions, was just as enjoyable.