This is a history book that answers the question: what did librarians do to help the war effort during World War II?
Well, a lot it turns out.
They amassed foreign periodicals and scoured them for intelligence information
They captured and cataloged information left behind in German facilities after they were abandoned
They scoured libraries and other collections for Nazi literature to destroy it (this one was controversial; many of them were very conflicted about this)
They found and attempted to return looted collections of boks after the war
There was a surprising amount of stuff going on in the library space during the war. Information itself was just another front in the war, and librarians served with their expertise.
A lot of people would find the book quite dry – I mean, the subject clearly isn’t a thriller – but I enjoyed it. There are a lot of interesting stories in there, and it builds toa slight climax at the end when many of the librarians are asked to destroy Nazi literature (to burn books, essentially), and some of them resign because of it.
And, of course, there are many parallels to The Monuments Men, which was the famous book (later a movie) about the art hunters who saved art from the Nazis. The book comes up a few types, and invites comparisons about the aesthetic and practical value of art vs. books.