I got to hear Ellen Butler speak at my local library a couple of months ago on the topic of women in the OSS. That's the Office of Strategic Services, if you don't know, the American intelligence service they created in the early days of WWII, which has since become the CIA. I watched the Alan Ladd movie O.S.S. (1946) earlier this year and was curious as to how accurate that representation might have been, and I'm always interested by anything to do with WWII anyway.
Butler was knowledgeable and engaging, and I very much enjoyed her presentation. I even raised my hand to ask if she'd seen Alan Ladd's movie and if it seemed accurate in light of her own research. (She said she thought it was accurate overall, so yay.) Butler has even managed to meet and interview some surviving female OSS agents, and her own grandfather served as a cryptographer during WWII. I found her fascinating.
As for The Brass Compass, it was overall most enjoyable as well. It follows Lily, a young American who speaks French and German flawlessly. She joins the OSS because she's bored and purposeless and is soon behind enemy lines, posing as a nanny so she can spy on a high-ranking Nazi officer. But her cover is eventually exposed, forcing her to flee across Germany in the dead of winter. She's eventually reunited with the man she loves, an American airman, and goes on to have more spying adventures with and without him. It's kind of an episodic story, with Lily having various spying escapades, and with the love story threading through all of it.
If This was a Movie, I Would Rate It: a soft R for violence and torture, mentions of rape, description of a Nazi death camp, bad language sprinkled throughout (including an f-bomb dropped by a soldier confronted with said death camp), and some non-explicit love scenes. Really, it's the torture that pushes my rating up from a PG-13.