PW: You're a devoted fan of Robert Louis Stevenson's The Strange Case of Dr. Jekyll and Mr. Hyde. What about it resonated with you?

Anthony O'Neill: I first read it when I was seven, so it's always had a special place in my psyche: the darkness, the sense of foreboding, even the gas lamps. It's probably not Stevenson's greatest novel, but it's extremely atmospheric, and I love losing myself in it.

PW: What inspired you to become a writer?

AO: Nineteenth-century novelists like Stevenson, Alexandre Dumas, Jules Verne, the Brontës and Arthur Conan Doyle. All of those influences come through in The Lamplighter.

PW: This psychological thriller, set in the 19th century, centers around Evelyn Todd, a onetime orphan who returns to Edinburgh after 20 years. She suffers nightmares featuring Leerie, a lamplighter, who is committing savage murders that are simultaneously playing out in real life. Two sleuthing duos are on the case, among them philosophy professor Thomas McKnight and his young Irish sidekick, Joseph Canavan. They bear a striking resemblance to two rather notable biblical figures, no?

AO: Yes. McKnight is the doubting Thomas and Canavan is meant to be Christ-like. Evelyn is Eve, and Leerie is Lucifer. The biblical imagery is definitely very potent.

PW: You probe the true nature of good and evil, introducing a sect of religious fanatics, including member Alexander Lindsay, the Calvinist director who lorded over the orphanage of Evelyn's childhood.

AO: There were definitely reactionary forces present in the 19th century. I'd like to think that the book is anti-extremist as opposed to antireligious.

PW: Evelyn had a boundless imagination as a girl, which proved especially threatening to Lindsay. Why?

AO: People are terrified of the realm of the imagination, its power, its limitlessness. We've all got to accept and explore the dark corners of our imagination without acting upon our impulses.

PW: Freud wasn't yet formulating his theories on the unconscious when this particular drama unfolds.

AO: I considered setting the book in Vienna at the turn of the century, but ultimately decided against it. McKnight could be considered a forerunner to Freud.

PW: As a 21st-century writer well versed in psychoanalysis, how were you able to resist the anachronism of Freudian analysis?

AO: I researched psychology to make sure that terms like the unconscious were in use in that form in the 1880s. People at that time were a little bit more advanced than I gave them credit for. Freud was probably just an extension of some other figures who'd paved the way for him.

PW: You offer comic relief in the form of Carus Groves, the official inspector on the case, who casts himself as a quintessential detective in the memoirs he pens at night. In reality, he is bumbling, incompetent and blinded by his own vanity.

AO: I hope the reader feels a bit of sympathy for Groves and wants him to succeed in his very vain ambitions. The base envies are in us all.

PW: How long have you been planning this novel?

AO: I've got notes going back to the early '90s. Originally it was called Damnation. I tried to conceptualize hell as a place that actually existed. But I thought it would defy credibility, so I came up with the idea that hell only exists in the imagination.

PW: How have you supported yourself over the years?

AO: As a stock coordinator in a warehouse. In a video store. In a bank. As a fuse salesman. There were years where I literally didn't earn a penny and lived off my savings. I am writing full-time now. It's a great privilege to be able to exercise your imagination and get paid for it—I'll never take that for granted.

PW: What's next?

AO: A mystery-adventure that involves Napoleon. I've done 18 months of research, and I'm about to start the first draft—I plan it like a military invasion. I plot everything out in advance. Then I can't wait to get everything on the page.