The second half of "Blackout" (they really should have been published as just one book). Although the premise of the book is that time travel is not only possible, it's a commonly used historical research tool, the book isn't really about time travel itself. It's about the characters: the historians from the future researching World War II England, and the actual historical events of World War II. Willis did a lot of very detailed research for this novel and whether or not the time travel aspect interests you, this is worth reading just to appreciate the absolutely incredible heroism and sacrifices that the entire nation made in order to beat Hitler.

It was particularly interesting to me since my grandfather lived in London during the blitz and helped in the rescue teams after bombings; and I have read some of the letters my grandmother wrote to her friends in Australia during the war describing the evacuations and the people trying to cope. But I think anybody would find the story makes the era a little more personal and approachable; Willis tells it as if she was there, and makes the reader feel as if they are.

I still would recommend one of Willis' other novels as a starting point for those who've never read anything else by her, but I enjoyed this lots and look forward to her next book, as always.