Richard North Patterson was a political novel ist, but he doesn’t write novels anymore. Non-fiction is too compelling.

Sitting in his West Tisbury home office amid piles of manila folders containing reams of research and drafts of upcoming political columns, he said, “I couldn’t make this stuff up, I mean, that’s the thing. I would hate to be a novelist trying to write a political novel right now, or even a political satire. You could take drugs for hours and not come up with this stuff.”

Staying true to this rich source material, Fever Swamp, Mr. Patterson’s latest book, is an accounting of the 2016 election. It contains his columns written for the Huffington Post from September 2015 to November 2016, complete with ex post facto annotations.

If this sounds triggering, well, that’s kind of the point.

“I don’t think people should lull themselves into, oh he’s going to become presidential, or… Jared and Ivanka for God’s sake are going to save him from Steve Bannon,” Mr. Patterson said. “What he has done is warp the dialogue of the nation in his own character. The nation hasn’t changed him, he is changing us. He’s changing us through the numbing untruth, through the lack of decorum and understanding, the constant reversals of course.”

The rapid-fire pace at which current events unfold might leave little time for reflection, but Mr. Patterson suggested his post-mortem of the election is vital today.

“People are still trying to put Trump in their little analytic boxes... but the truth of it is, the organizing principle for everything he does is narcissistic personality disorder. I wrote that 14 months ago, and if you look through what I wrote — at that time, before, and after — I think you really do understand who this guy is and how he’s going to behave, and I don’t think there’s any escaping it.”

As a political novelist-turned-columnist, Mr. Patterson has a unique set of qualifications to make these kinds of assessments. In Fever Swamp, he cites his varied background as a key credential. “But perhaps most helpful in this strange and unsettling year was three decades spent as a novelist,” he writes in the book. “Essential to this was the study of character—including motivation and psychology and how they played out under the pressure of events.”

He also noted his training as a lawyer, the connections he’s developed over the years as a political novelist, and his perspective as an outsider to journalism as additional qualifications.

Making the switch from fiction to opinion writer changed his writing process, he said. As a novelist he wrote every weekday and took summers off. Now he’s beholden to the 24-hour news cycle. “I don’t control this in the same way. It more controls me,” he said, citing Mr. Trump’s Twitter presence as one example of this phenomenon. Mr. Patterson said he tries to avoid Twitter as much as he can, though, while still staying up to date. He described the site as a chance to make a fool of yourself every hour.

It’s that same kind of humor that Mr. Patterson brings to his writing. “Humor, it has a value in itself,” he said. But, he added, “Humor is also an effective way of pointing out issues, problems or just the sheer incongruity of a political moment.”

Fever Swamp seizes on these incongruities. Divided into five sections that trace the election from the primaries through the day after the election, it’s part ghost story, part psychodrama and part elegy. And it’s all 100 per cent true.

Richard North Patterson will speak on Saturday at 11 a.m. at the Harbor View Hotel, and on Sunday at 2:45 p.m. at the Chilmark Community Center.