“You Should Have Known” by Jean Hanff Korelitz. (Grand Central Publishing/TNS)

Sometimes, the book is better.

Maybe you got pulled into “The Undoing” on HBO a few months back. A psychological thriller starring Nicole Kidman as a well-off New York City therapist and Hugh Grant as her debonair doctor husband who’s definitely not what he seems (and possibly may be a murderer), it was a series that promised a lot (think “Big Little Lies,” Manhattan version) and ultimately didn’t really deliver (except for Kidman’s character’s coats, which were sublime and which absolutely deserve to be spun off into their own series).

Author Jean Hanff Korelitz said in interviews that she had no idea how the series would end, as her book, “You Should Have Known,” was quite different. It’s so much better. (Minor spoiler alert here.)

Like the series, “You Should Have Known” has therapist Grace at its center; unlike the series, it’s solely about Grace because her husband, Jonathan, doesn’t appear at all — the story begins after his disappearance (Grace initially thinks he’s at a medical conference), and we come to know him only through Grace’s memories.

And, since we’re not distracted wondering when Grant will show up and say something charming, we can focus on the book’s fascinating premise: how a woman who has based her career in telling others how to pick the right person can do exactly the opposite for herself, and how a picture-perfect life can excruciatingly unravel.

Having watched the series doesn’t spoil this book it all; it just makes you read it appreciating the book’s nuances (Grace and her family, for example, are nowhere near as wealthy as they are in the screen version), its perfectly spun tension, and its portrait of a smart woman slowly realizing her own blind spots. Check it out — and note that Korelitz has another literary thriller out in May, “The Plot.”