“Under the Dome” gravely threatens Stephen King’s status as a mere chart-busting pop cultural phenomenon. It has the scope and flavor of literary Americana, even if Mr. King’s particular patch of American turf is located smack in the middle of the Twilight Zone. It dispenses with his usual scatology and trippy fantasy to deliver a spectrum of credible people with real family ties, health crises, self-destructive habits and political passions. Even its broad caricatures prompt real emotion, if only via the damage they can inflict on others. Though the book’s broad conspiratorial strokes become farfetched, its ordinary souls become ever more able to break hearts.

This book has the heft of a brick. It also has a premise that can be summarized in seconds. On a beautiful autumn day in Maine a transparent dome materializes over the town of Chester’s Mill. Once the Dome falls, all vestiges of normal life are suspended. Things run amok. They get scary. The townsfolk become fate’s playthings. And Mr. King, who can manipulate this crisis in any way that occurs to him, becomes a kid in a candy store.

The premise provides so many options that Mr. King’s decisions about how to tell this story are of special interest. The King book that is most readily brought to mind by “Under the Dome” isn’t an earlier large-scale apocalyptic fantasy like “It” or “The Stand”; it’s “On Writing,” the instructive autobiographical gem that cast light on how Mr. King’s creative mind works. In the spirit of “On Writing,” “Under the Dome” takes a lucid, commonsense approach that keeps it tight and energetic from start to finish. Hard as this thing is to hoist, it’s even harder to put down.

Consider the book’s step-by-step way of defining the Dome. Mr. King isn’t about to do the easy thing, which would be to give a straightforward description of what it is and how it works. Instead he offers a textbook demonstration of how to make action and explication one and the same. First step: A woodchuck on the ground and a pilot in the air named Chuck are sudden victims of the Dome’s guillotinelike slicing descent.