Hear Maria Semple read on October 8 at Town Hall.

Maria Semple's consistently funny third novel, Today Will Be Different, tracks a woman's existential crisis over the course of a single day. Eleanor Flood is a funny, upper-middle-class Seattleite who has a cool job as the animation director for a successful cartoon. She has a family (and a little dog, Yo-Yo, too) that tolerates and even loves her "unrelentingly verbal" nature. She's working on a big comic book about growing up with her sister, Ivy, called The Flood Girls, and she's studying with a poet, Alonzo, to sharpen her already sharp brain for the benefit of the book. In short, she's a well-off woman who has it all.

But! She has struggles.

She suspects her husband, Joe, a kind and practical and levelheaded person who everyone automatically likes, might be cheating on her. Their 20-year marriage has officially entered its sex-neutral companionate stage. She wishes her precocious and maybe genderfluid kid, Timby, would like her more than he does, and fears she's losing him to technological distractions and a gender identity she doesn't understand—and admittedly "aggressively" took no interest in before he started wearing makeup. Mostly, she wants to be the linchpin that holds the family together, but nobody seems to need her. On top of all that, the first draft of The Flood Girls is very late.

The book's flaw is that it fails where it seems to want most to succeed. The intense suspicion of her husband's infidelity is really, Eleanor tells us, just a cover for the deep feelings of loss she has for Ivy. That loss is supposedly the true source of Eleanor's crisis, but it's the least convincing of her character motivations in the book.

Most of the language about Eleanor's sister is cliché or kinda mean. Here's the Big Emotional Moment, where Flood describes her longing for Ivy: "The comfort, the thrill to have her sitting beside me. To again have a sister who 'always came by,' as Spencer put it. Just imagining Ivy's flesh and her limbs, something within me rises up, the Flood girls once again, ready to conquer the world."

That's exactly eight clichés from a writer who does not use clichés, who is blindingly good with detail. The whole New Orleans section of the book, where the backstory between Eleanor and her sister's falling out is explained, doesn't focus on Ivy. Moreover, Eleanor constantly positions herself as second to Ivy in terms of physical appearance and temperament. Everyone loved Ivy, but people only ever liked Eleanor. About the only compliment she gives her sister, aside from noting her thin and slender beauty, is that her time in the South allowed Ivy to "grow into her fragility." The only time you see the two women having a good time with each other is during a flashback at a doctor's office, which is when Eleanor meets her husband for the first time. Both Ivy and Eleanor are hammered, fawning after Joe. By the time Eleanor gives Ivy her big wedding gift, a copy of The Flood Girls, their childhood story, you can't believe there'd be much in there to celebrate. Semple even includes a selection of the comic book in Today, and in the three photos you see of the sisters together, they seem distant from one another. In one, Eleanor has her back to Ivy; in another, they sit about two feet away from each other on a stoop. The only time they're touching in a loving way is when they're babies.

The heart of this book, the parts Semple wraps the best language around, is Eleanor's fear of her chosen family's rejection. Her aging body makes her feel inadequate, and she uses buckets of hilarious, fresh-seeming self-deprecatory language about that. The absurd lengths she goes to and the level of creativity she employs to seek out her husband's secret are the funniest, most moving parts of the book. In these moments, Semple's humor is tight and self-aware. Her scene-setting abilities amaze. (It's almost as if she used to write for Arrested Development and Mad About You!) You breeze through these sections, not because the writing's simple but because the dialogue feels so natural, and the quotidian details are put-the-book-down-and-laugh true.

So Today is a great book about a woman who thinks her husband is cheating on her and so goes to bizarre lengths to discover the truth, but it's a not-that-great book about a woman who is doing all of that because she secretly deeply misses her sister. recommended