Ahhh, how great to be back in Seattle, to the most precious and lampoonable version of that city as seen through the worried eyes of Eleanor Flood, the narrator and antiheroine of Maria Semple’s inventive third novel, “Today Will Be Different.”

(Little, Brown)

Eleanor is chronically disappointed in herself, in her versions of wife- and motherhood; in her degrees of kindness, friendship, organization, pet ownership and yoga attendance. She is a graphic artist the way Bernadette of Semple’s genius second novel was an architect: in the past, with baggage and regrets. Clearly talented — not her boast — she’d once been the artistic director of an animated television series, “Looper Wash,” about four girls in ’60s-style pinafores and tangled hair who have an “unconscious fear of puberty.”

After almost a decade in “dumpy Washington State,” a fish out of New York waters, and about to turn 50, she is trying hard to be her better self despite a “constant low-grade state of confusion.” Her fallback is “The Trick,” so labeled by one of the nine shrinks she’s seen in the past 20 years who “handed me back my check and wished me luck.” Its manifestation: “If I see you about to criticize me, I leap in and criticize myself . . . so afraid of rejection that I turned every interaction into a life-or-death charm offensive.”

Shouldn’t baby steps toward self-improvement be as easy as a Sunday drive, she wonders? No. “Then that prankster Reality appeared in the pickup truck ahead of me and started tossing watermelons out the back.”

Among the goals she’s not meeting is sex more often with her husband, Joe, a famous yet modest hand surgeon. We love him, too, this man who treats everyone the same. As Eleanor points out, “You’d have to draw him a picture to explain why it’s cooler to save the pinkie of a Cy Young Award-winning pitcher than the wrist of a checkout lady with carpal tunnel.”

Semple’s descriptions — no surprise to her fans — are loopy, deeply and darkly funny, and brave. Watch out, Seattle, which gets it from both sides: A restaurant has “ebony walls, industrial ceiling, fabulous bursts of geometric music, and whimsical, but not too whimsical, chandeliers.” A state fair, on the other hand, horrifies the native New Yorker with its “parolee vibe.”

Among the novel’s most endearing wiseacreage falls between Eleanor and her third-grader son, Timby, whose transgender inclinations secure instant admission to the Galer Street School and its “fervent embrace of everything.” (Galer Street was daughter Bee’s “ruinously expensive private school” in “Where’d You Go, Bernadette.”)

“Mommy time,” the pediatrician recommends and Eleanor tries out on Timby, who is more familiar with his mother’s impatience and anxiety, best experienced at a safe distance.

“ ‘Mommy time?’ he said, not unafraid.”

Don’t be nervous when I tell you that “Today Will Be Different” takes place over the course of a single day. This is Semple at the wheel with dialogue-perfect Timby in the back seat, racing from drop-off at school, to breakfast with Alonzo Wrenn (her regular Thursday-morning poetry tutor, hired with the hope that memorizing poems will improve her vocabulary and lucidity); back to school to get Timby (alleged stomachache); to the pediatrician; to her husband’s office, where his absence feels maritally ominous; then lunch with a passive-aggressively grateful ex-“Looper Wash” employee; to the Olympic Sculpture Park; and onward to a destination that might reveal Dr. Joe’s new obsession.

Almost exactly halfway through the novel there is a return, novella-like, to Eleanor’s past and the love she has lost, that of her younger sister, Ivy. The interloper and villain is Ivy’s husband, Barnaby “Bucky” Fanning, a spoiled, red-faced, bullying only child of “two of New Orleans’ finest families.”

Author Maria Semple (Elke Van de Velde)

It is Eleanor’s wedding present, a hand-drawn scrapbook titled “The Flood Girls,” that offends the impossible Bucky and causes “the shameful estrangement” of the sisters. Inevitably, because of Eleanor’s New York City/non-Southern manners and alleged faux pas, Bucky turns Ivy, a near-Stockholm-syndrome wife, against her adoring older sister.

This New Orleans section switches to the third person. Wisely, Semple doesn’t leaven the heartbreak with her trademark black comedy. How does she do in that more somber tone? Beautifully. Of course, she can’t wholly abandon wryness: A girl comes, unforgivably, to a party at Bucky’s “on the arm of her boyfriend, a film major, last name Geisler. Not German Catholic.”

Ivy’s rejected wedding gift is ours to see. The novel includes 16 pages of beautiful illustrations, proof of Eleanor’s “sherbet-colored aesthetic.” If only she wasn’t eight years past the deadline and the assigning editor hadn’t switched careers, “The Flood Girls” could be expanded into a graphic novel.

Eventually, we find out what’s up with Joe, whose unexplained absences beg the question: Was there someone else? Despite an upping of the activity from frenetic to madcap, the reveal to some may be underwhelming. The sentences that get us there are not. Semple is a master of the social skewer, boldly impolite and impolitic, illustrating “the agita surrounding one normal day of white-people problems.” Tomorrow could be different for our antiheroine. She’ll initiate sex, look people in the eye and at least try to score tickets to see the pope, who’s heading Seattle’s way. Eleanor is as sharp and Semple-esque as they come, which is to say a delightful danger to herself and others, sympathetic, and so very smart.

Good luck, Eleanor Flood. We’re rooting for you.

Elinor Lipman’s 11th novel, “On Turpentine Lane,” will be published in February.

On Nov. 3 at 7 p.m., Maria Semple will be at Politics and Prose, 5015 Connecticut Ave. NW, Washington.

Today Will Be Different

By Maria Semple

Little, Brown. 259 pp. $27