ON ANY GIVEN day of the week, the El will rocket across SEPTA's Market-Frankford Line, ferrying people from one corner of the city to another.
They'll all be wrapped up in their own worlds - the young guy bobbing his head to an unheard beat, the mom who's trying to get her toddler to quit squirming, the junkie who says he just needs 50 cents to get a bite to eat.
Duane Swierczynski will be sitting there, watching them. And then his mind will start to wander.
What if the train suddenly screeches to a halt and goes dark? What if a sinister killer is lurking on board?
These imaginary scenarios will play out, one after another - and some of them might end up in Swierczynski's next book.
In the last decade, the prolific-yet-humble writer has authored more than a dozen crime novels, six nonfiction books and an ever-growing list of comic books, including Judge Dredd, Godzilla, and Cable, a longtime cog in Marvel's X-Men universe.
His critically acclaimed work has caught Hollywood's attention. Actress Michelle Monaghan, who starred in the HBO series "True Detective," has optioned one of Swierczynski's books to be made into a movie, a tech-thriller called "The Blonde."
The 42-year-old Frankford native often turns to his hometown for inspiration.
"Philly is where my imagination goes to play," he says. "I've always been fascinated with this city."
Swierczynski, a former City Paper editor, recently talked with David Gambacorta about his early work in true crime and the projects he has coming down the pike.
Q Your first book, "The Encyclopedia of the FBI's Ten Most Wanted List: Over Fifty Years of Convicts, Robbers, Terrorists, and Other Rogues," was rereleased in February by Skyhorse Publishing. How did that project come about?
I had an agent back in the late '90s who found an editor who needed an encyclopedia of the FBI's Most Wanted lists. I thought a magic FBI office would open and someone would say, "Here are all of our files on all of our fugitives!" But it turned out to be a four-year process of digging up really obscure articles. It was like my Vietnam; it never ended.
Q Which fugitives interested you the most?
I like the more obscure ones. There's one guy, this South Philly gentleman named Freddy Tenuto, who really fascinated me. I want to do a whole book on him. [Tenuto was convicted of murder in the early 1940s, and later broke out of Eastern State Penitentiary.] My grandfather grew up with him. He joked that Tenuto still owed him five bucks.
Q You've set a number of your novels - and a comic-book storyline involving Marvel's "The Punisher" - in Philly. What keeps bringing you back?
I love books that have real, concrete settings. Five or six of my books have been set here, and the next four or five books that I have planned in my head are all Philly-centric. . . . I ride the El and think, "What would happen if there was a gunfight right now?" My imagination is stuck here.
Q Between comic books and your novels, you have a lot going on. How do you juggle everything?
I do keep a lot of worlds alive in my head. I just hit "pause" on one thing and move on to the next. Right now, I'm working on a horror movie with a friend of mine, and I'm also doing a plot for "Judge Dredd" - and doing research for my next novel.
Q Was it hard to leave City Paper in 2008?
I think I went home and curled into a ball and almost cried. But I don't regret it. I believe you have to be all-in with whatever you choose to do, and, at the time, I felt that the fiction stuff was really pulling me.
Q Your first hardcover, a set-in-Philly story about a drug informant called "Canary," is coming out next February. Anything else on tap?