“Watergate” is the fourth novel Thomas Mallon has set inside the Beltway, and it’s certainly the most ambitious. The novelist, who has lived in Washington for nearly a decade, imagines the scandal from the perspectives of its primary participants, including President Nixon.

Why did you decide to fictionalize one of the most written-about political events of the 20th century?
I guess it all starts with Nixon. He was the public figure who dominated my life. I was an ardent Nixon supporter when I was 9 years old, and I would tell my classmates that I didn’t think Kennedy had enough experience to be president, which strikes me as a preposterous position for a fourth-grader.

What can a novelist do with this material that a nonfiction writer can’t?
Speculate. “Watergate” isn’t what’s called alternate history, but you have the opportunity to insert things in the cracks. What the novelist can do is take a well-known story and try to get readers to think about it in a different way, to experience it with a new intimacy.

What attracts you to D.C. as a setting for so many books?
The city is an endless font of stories. When I wrote “Henry and Clara,” about the couple in the balcony with the Lincolns on the night of his assassination, I remember thinking if you just look at all the real-life stories that took place in Lafayette Square, you’d never run out of material.

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