William Dietrich delivers his third historical, The Dakota Cipher, about American adventurer Ethan Gage.

Who was your inspiration for Ethan Gage?

I enjoyed the twist on the conventional British imperial hero represented by George MacDonald Fraser's Flashman, about a likable cad. I thought an irreverent American from an infant nation could provide a fun perspective on the Napoleonic era very different from such fictional standbys as Forester's Hornblower, O'Brien's Aubrey and Cornwell's Sharpe.

Why did you choose the Napoleonic era?

The Napoleonic period is when our modern era began: political movements that convulsed whole nations, the infancy of the industrial revolution and life lived like grand opera. There were brilliant uniforms, courageous charges you might actually survive because weapons were inaccurate, careers that could end at the guillotine or firing squad, tumultuous love affairs, reckless glory, far-flung campaigns, scandalous clothes, fevered furnishings, tall ships, thundering horses... Mon Dieu!

Is it a challenge for you to present Ethan in a good light? He misbehaves so badly.

Ethan is likable because he misbehaves, or rather, because he is so human. Like all of us, he's a mass of contradictions, pledging to do good while succumbing to temptation, admiring idealism while recognizing the venality of his contemporaries, confusing love and lust, and luck with ability.

Do you ever find yourself having to rein Ethan in because his escapades might contradict historical fact?

It's tricky. Ethan must play an important role and exhibit dogged pluck and persistence, but he cannot become a superhero because that eliminates the peril and shatters the reader's concession that my yarn is plausible. His adventures have to roughly fit within the bounds of historical possibility. Fortunately, this era was so rich with real outlandish adventures that I invent much less than I record.

Ethan's exploits also frequently expose him to magic and supernatural secrets of the forgotten past.

Ethan's quest for ancient secrets and historical treasures are the frosting on my concoction—or maybe the base. I'm intrigued by the puzzle of how civilization began, what ancient secrets might have been lost and whether worldwide legends of mysterious ancestors who started it all have some root in truth.

What intrigues are in store for Ethan in his next adventure?

Ethan returns from America to Europe, where he forms a quartet of enterprising scientists, runs afoul of the Barbary pirates and makes dramatic use of some famous inventions. And, yes, his lover, Astiza, will reappear, and in a surprising and challenging way.