In The Spaceship Next Door (HMH/Adams, Sept.), a teen girl guides a reporter’s investigation of a spaceship that crashed in her town and has lain dormant for three years.

One protagonist, Annie Collins, is a teen, but the other, reporter Ed Somerville, is an adult. Did you have a target audience in mind as you wrote their story?

No, not really. I was just writing to see what came out at the time. Honestly, she’s 16 in part because I didn’t want to deal with her being 22 or 23 and somebody assuming that there’s going to be some sort of romantic entanglement for her, because I didn’t think that needed to be part of the story. So my original impetus behind making her 16 was just to avoid that. It ended up being a very good decision. The idea of taking a character who’s going to save the world and making her the most vulnerable on the face of it appealed to me. And I think writing for girls and women is more fun anyway.

You have an entire ensemble of alien watchers camped out near the ship. How did you come up with their wildly varied theories?

I’ve always been interested in people who believe unusual things absent any available evidence. I’ve spent some time writing an online column in which I discussed various beliefs in, take your pick: aliens, telekinesis, various pseudo-sciences. I spent a lot of time exploring what was out there and trying to come to grips with why people believe those things, so I think it was a natural fit for me be able to say, “Well, here’s this situation where you’ve got something that definitively happened and then nothing has happened since.” What would that do to people who are ready to believe whatever their minds can concoct and then try to backfill facts to support what they believe?

Besides your novels, you’ve written for stage and screen. How have those disciplines affected your novel writing?

I haven’t done either of those things for a while. I’m a natural writer of dialogue, that’s where I tend to drift with my books, and so the challenge as a novelist has always been how to not rely too much on dialogue and deny my instinct to do so. I think that I learned a great deal when writing plays in figuring out how to pace every story I tell. Plays are where you learn what a three-act structure is. I would argue that Spaceship Next Door is a Chekho-vian play structure, it’s a two-act structure—unless you want to count the first chapter as act one, which I wouldn’t.