The Bangkok to Chicago flight was about to board. Our hero shuffled toward the gate, exhausted after three weeks away from home, pinballing across Japan and Thailand. A terrible realization dawned:

It’s a 14-hour flight to O’Hare. And he … had nothing … to read. Acting on instinct, he bolted into a small gift shop, spun a black wire rack. With experienced fingers he deftly plucked up “The Cardinal of the Kremlin” by Tom Clancy.

That book saved my life. I’d have gone mad otherwise. It was also the last thriller I read until Wednesday, when I was rushing out the door, toward a long weekend in Washington, D.C. The cab was out front. “Oh a book!” I thought, grabbing “Shadow State” by Frank Sennett.

Why that book and not, oh, “Theogony Works and Days Testimonia” by Hesiod, also waiting to be read? First, “Shadow State” was published last week. Second, Sennett is a Chicago author, longtime journalist, now mellowed into public relations. We had lunch once.

As someone who left nine books on the doorsteps of many a media acquaintence who just shrugged and let them die there, squalling, ignored, I feel a moral obligation to at least start any book sent my way. To read the first page. Usually the first page is plenty. Most books are crap.

“Shadow State” isn’t crap. I kept reading. There’s no choice.

It starts with ex-Ranger sniper Rafael Hendrix, now in the Secret Service, gazing through the scope of his high powered rifle at a terrorist bomber who has taken a fifth-grade class hostage, including his daughter Becca and the First Lady.

He has a choice. His orders are clear.

“Do not take the shot. Repeat: Do not take the shot. Acknowledge.”

I imagine regular readers of thrillers, which I am not, know where heroes land when it comes to doing what they’re told. The action takes off there and never stops.

I don’t want to give anything away, because you’ll want to read “Shadow State.” Hendrix, a vet of the Afghanistan war, must catch a wily, cruel terrorist — or is that “terrorists”? — while protecting the president of the United States, who is a Black lesbian amputee who served with Hendrix in Afghanistan.

Sennett got his MFA at Montana, where he was born, and the writing has a Great Plains austerity Not a lot of showy language, though he does offer several nice turns of phrase, like, “He’d opened himself up to the universe, as his ex-wife had always put it, but the universe hadn’t noticed.” And a three-word sentence that explains much of what is wrong with our world, “Distraction trumped compassion.”

The book hooks readers and pulls them along through a series of events that defy summary. As the body count soars, various historic assassinations and attempted assassinations of presidents become a major plot point, and we learn fascinating details about the “Baltimore Plot” that had Lincoln sneaking into his own inauguration.

Sennett draws a line between the aggrieved hateful losers who went after Lincoln to the aggrieved hateful losers challenging democracy today: “A hundred and sixty years between those conspiracies, Hendrix thought, and the exact same strain of white supremacist malcontents had run a similar playbook to keep a legally elected President from taking office.”

This is a thriller for liberals, and a welcome reminder that liberals also love their country. They are equally passionate Americans fighting to preserve our nation, not pretend patriots imagining tiny grievances. They are defending cherished ideals, not undermining them.

Plausibility is important to me, and I admit, at times, the tumble of fortuitously uncovered clues and jarring plot reversals made me wonder if we’d strayed from the realm of the possible. But that’s the form.

Riding the Washington Metro, lost in “Shadow State,” I almost missed my stop because I was engrossed in Sennett’s taut narrative and thrill-a-minute prose. I slammed the book shut and hurled myself through the doors just as they were closing, quite Rafe Hendrix-like.

Sitting at gate C32 at Ronald Reagan Washington National Airport, I reached the end of “Shadow State,” heard an audible sob somewhere, took off my glasses and wiped a knuckle across each eye.

Frank Sennett’s “Shadow State” is a smart, lean, action-packed political thriller that pulls you in on the first page and doesn’t let you go until the last, when Sennett promises, “Rafe Hendrix will return.” Can’t wait.