‘Dept. of Speculation’ by Jenny Offill

Jenny Offill. Michael Lionstar

There is a species of agonizing pain that the human mind cannot assimilate immediately upon waking. It takes a moment before the gut lurches, the eyes tear, the ground gives way: The memory has returned and gaping terror sets in, because whatever’s been lost is still lost.

This is the sort of pain in which Jenny Offill’s slender, quietly smashing novel “Dept. of Speculation” deals, recollecting a marriage mortally damaged by betrayal.

“People say, You must have known. How could you not know? To which she says, Nothing has ever surprised me more in my life.”

That’s because first came happiness, even bliss, inside a domestic cocoon whose making had never been at the top of the woman’s list of aspirations. She is a writer and meant, for years, to devote herself mercilessly to her art.

Instead, she found those plans buried by the slow-motion landslide of the day-to-day: the husband who loves her, the serious little girl who makes them laugh, the mercenary jobs that pay for diapers and baby sitters and bedbug exterminators.

“He is famously kind, my husband,” the woman tells us, though we don’t know her name, or his either. “He’s from Ohio. This means he never forgets to thank the bus driver or pushes in front at the baggage claim. Nor does he keep a list of those who infuriate him on a given day. People mean well. That is what he believes. How then is he married to me?”

The story shifts and skitters, spare but intricate as filigree, short bursts of observation and memory — comic, startling, searing — floating in white space.

For a time in their daughter’s toddlerhood, her favorite book is about firefighters, and the man “reads the book to her every night, including very very slowly the entire copyright page.”

Just before teaching her writing class, the woman finds vomit in her hair. It’s disgusting, of course, and proof of exhaustion, but also proof of the golden trio they’ve become. For such precious entities, great sacrifices are made.

Listen: “I would give it up for her, everything, the hours alone, the radiant book, the postage stamp in my likeness, but only if she would consent to lie quietly with me until she is eighteen. If she would lie quietly with me, if I could bury my face in her hair, yes, then yes, uncle.”

Offill has tapped a vein directly into the experience of this marriage, this little family, this subsuming of self, and we mainline it right along with her.

So when the betrayal comes, it is horrific, enraging. It is also banal, a mortifying cliche of middle age. The man gets involved with a pretty young creature at work.

It’s as if the skin has been torn, strip by strip, from his wife’s body. But there is no kill switch for love, and treacherous behavior does not obliterate all that came before. The woman has reason to cherish what she’s cherished.

“The thing is this: Even if the husband leaves her in this awful craven way, she will still have to count it as a miracle, all of those happy years she spent with him.”

On the street one day, the woman runs into an editor she used to know, years ago.

“I think I must have missed your second book,” he says, meaning kindly to draw her out, and then things get awkward because she hasn’t written one.

Fifteen years ago, Offill made an auspicious debut with “Last Things,” her first novel. “Dept. of Speculation” is her second. It is a book so radiant, so sparkling with sunlight and sorrow, that it almost makes a person gasp.