The last time I skimmed this is was for my own book. I enjoyed what I read so much that I put it on the shelf to come back to, and then spent last week reading it cover to cover.

Highly recommended. A rethinking of some evidence people (mostly men) have looked at before while introducing new material discovered while researching the book after this (so glad I'm not the only person who gets distracted this way). Akkerman steps back from assumptions, interrogates language and genuinely seeks to situate these women within their own times and mores which--and this is unusual--keeps a firm grip on the idea that there was no one way of thinking about women and their morals, and that class and religious allegiance played a large part. Her untangling of Anne Halket's biography is particularly fascinating in this regard, as she demonstrates that Halket's 'sin' is not her marriage to a bigamist, but the lies she had to tell as a spy.

After you've read this I recommend following it up with Pete Langmann's Killing Beauties which uses Akkerman's material for a novel of Civil War spies.