Blackout, Willis. Yes. In the acknowledgments (I think it is), Willis mentions that this story grew from one book into two, and I think I saw quotes from her talking about how there was a lot of material that she had to discard. I mention this because I frequently got the notion while reading Blackout that it had been padded, like maybe the story grew to about a book and a half, and Willis’s editor encouraged her to round it up to two. I just don’t remember feeling quite so impatient with previous stories in this setting.
That said, it’s Willis, and therefore worth reading. It may be my least favorite of the Oxford time-travelling History department works thus far, and I certainly hope that All Clear makes me happier, but none of that changes the fact that Willis is an extremely strong writer.