Willis explores individual heroism and responsibility in her latest time travel tale, Blackout.

Blackout is the first half of the story, with the second half, All-Clear, scheduled to appear in November 2010. Why was the book split into two volumes?

Blackout/All-Clear was one book that grew, sort of like the Blob. Books should never be too fat to read in bed or take up all the memory on a Kindle, so my publisher split it up. I hope the wait between the two books will whet people's appetites rather than just annoying the heck out of them.

Your Nebula- and Hugo-winning story “Fire Watch” shares a setting with Blackout and echoes some major plot points. What's the relationship between the two?

The intense attack on St. Paul's Cathedral in London on the 29th of December, 1940, plays a pivotal role in both stories. That was the night the Luftwaffe attacked the city with wave after wave of incendiary bombs. St. Paul's was hit with 29 bombs in little over an hour and was only saved by the heroic efforts of the fire watch, who may have won the war with that action. It's not necessary to have read “Fire Watch” to understand what's going on in Blackout/All-Clear, but for my long-time readers, it's an extra pleasure.

What's the appeal of setting stories during the London Blitz?

I love the pluck and stamina of the British and the humor and courage with which they held out against Hitler. And I love the intensified nature of wartime existence, where a few minutes' delay can cost you your life and a mistake or a change in the weather can alter the entire course of the war. I think those things are always true in our lives, but they're ramped up during wartime, where every decision is life-or-death.

You've been writing science fiction for over 30 years. How has the genre changed during that time?

At my very first writer's conference, George R.R. Martin said to me, “It's a pity you're getting into science fiction right now, because it's on its last legs.” Not only was that not true, but now you can't turn on a TV without seeing our influence everywhere, and some of the best science fiction I've ever read is being written right now. Science fiction is an amazing literature: plot elements that you would think would be completely worn out by now keep changing into surprising new forms. I have great faith in the future of books—no matter what form they may take—and of science fiction.