“The Starter Wife” is the most maddening kind of show.

Just when it seems this six-part USA miniseries is about to topple under the weight of its own preposterousness, amid a sea of tired romantic clichés, out pops a gem of a scene or a bit of whip-smart dialogue.

In these moments of hilarity and insight, which come every 10 minutes or so, "Starter” proves that it has the capacity to be so much better than in it is. If ever a show’s parts were greater than its whole, this is it.

Based on the book by Gigi Levangie Grazer (mega-producer Brian Grazer’s wife), and starring Debra Messing (“Will & Grace”), “Starter,” which airs on Thursdays at 9 through June 28, is an of-the-moment amalgam of “Sex in the City” and “Entourage,” combining the former’s upscale quartet of fashion-conscious friends and the latter’s fascination with Hollywood backbiting and deal-making.

Messing, as the miniseries’ heroine and narrator Molly Kagan, guides viewers through a complicated maze of entertainment industry relationships as she tries to navigate them herself. And absent the neuroses of her Grace character, Messing is much more appealing here.

Yet her warmth and wit are consistently undermined by narrative-halting dream sequences and outlandish romantic situations that strain credulity and sympathy. Some are so absurd that a daytime soap wouldn’t attempt them, as when Molly has a soul-baring Starbucks date with a handsome, homeless beach bum who hangs out near her Malibu digs.

The story centers on Messing’s Molly, wife of self-involved studio executive Kenny Kagan (Peter Jacobsen, “61*”) and organizer of his overscheduled life.

Literally overnight, Kenny demands a divorce and takes up with a Britney-like tartlet. Molly becomes a pariah, losing her primo restaurant tables and cushy gym membership. She is abandoned by almost all of her friends.

The ones that stick around include Joan (Judy Davis, “Husbands and Wives”), the hard-drinking wife of a much older man, who lends Molly her Malibu beach house while she reluctantly goes to rehab.

There’s Rodney (Chris Diamontopoulos, “Charmed”), Molly’s gay interior decorator, who offers her moral support, even as his own business is floundering.

The fourth in the quartet is Cricket (Miranda Otto, “Return of the King”), who is being pressured by her director husband to dump Molly so he can secure a film deal with Kenny’s studio.

“Starter” works best when it focuses on Molly’s attempts to create a new life. As a former writer who gave it all up for marriage and motherhood, she has an untapped reservoir of bitterness over what's she given up and where that's left her.

When she releases her anger, often in biting, acid-tongued rants (“Of course I’m cranky. I haven’t eaten in 12 years!"), there's a rush that comes from seeing the evolution of a long-suffering, politely corseted good wife. Messing obviously enjoys playing a woman rediscovering her confidence, and her sexuality shines through.

Her scenes with Davis are equally crisp, especially one gem where the two women pretend to be dysfunctional, battling sisters in order to trick a rehab doctor into letting Joan out early.

But those rare engaging moments are far outnumbered by the most flaccid sort of exchanges.

The interaction between Molly and the beach bum (Stephen Moyer, “Quills”) feels like something out of a Harlequin romance. That may be partly intentional, but the effect is to unravel the delicate charm that Messing and the other stronger characters have worked so hard to weave together.

Similarly, the dream sequences are disruptive, and sometimes downright cartoonish.

That leaves “Starter Wife” at about 30 percent good, 70 percent muck.

The question is: How much muck are viewers willing to wade through for the good stuff? If USA decides to give “Starter” a full-series pickup, here's hoping the writers tweak those percentages. Better they flip them.

“Starter Wife” deserves better.