NBC is still seeking to master the formula for a gay-straight, three-headed family comedy, following up “The New Normal” — in which a straight woman played surrogate to a gay couple — with “One Big Happy,” in which a lesbian plans to have a baby with her bachelor friend, who suddenly winds up in a monogamous relationship. Produced by Ellen DeGeneres, the series advances the story in semi-serialized fashion, but is pitched so broadly that its politics take a back seat to pratfalls and rim shots. “The Voice” is helpful in introducing comedies, but this still feels like one big waste of time.

The network did send out a whole bunch of episodes in advance of the premiere, which suggests a greater level of confidence than the series appears to deserve.

Elisha Cuthbert (“24”) stars as Lizzy, who in true sitcom fashion literally babbles out the entire plot during a breathless over-the-counter exchange with a pharmacist during the show’s opening moments. See, she’s decided to have a baby with sperm from her childhood pal Luke (Nick Zano), thus flipping the “Straight woman/gay friend” combination that has become such a staple.

The road to motherhood is suddenly complicated, however, when Luke instantly falls for the extremely cheerful Prudence (Kelly Brook), who not only reciprocates his admiration but also needs a Green Card to stay in the U.S., lest she be shipped back to England. So control-freak Lizzy, no longer able to count on Luke’s unwavering time and commitment now that he’s chosen to wed Prudence to avoid losing her, suddenly has to deal with a third wheel to grease her plans.

As written by Liz Feldman (“2 Broke Girls”), Cuthbert might get all the pained reaction shots and most of the tart lines, but given how predictable the writing is — including the roles of the supporting players — Brook (whose overflowing resume describes her as a model, actress, host, businesswoman and pin-up) might be the key to the show’s prospects, with her character representing a free-spirited ray of sunshine and optimism, complete with fleeting (carefully obscured) nudity.

Otherwise, “One Big Happy” is one of those calculated illusions — a series that tries to appear forward-thinking and edgy by tackling the evolving definition of family and parenting, only to filter those elements through a musty sitcom template that predates “Ellen” coming out of the closet. In that regard, it feels compatible with its lead-in, “Undateable,” which qualifies as damnation with faint praise.

So while NBC’s opening-act scheduling might generate some old-fashioned sampling, there’s little here to inspire many “Happy” returns.

TV Review: ‘One Big Happy’

(Series; NBC, Tues. March 17, 9:30 p.m.)

  • Production: Filmed in Los Angeles by a Very Good Prods. in association with Warner Bros. Television.
  • Crew: Executive producers, Liz Feldman, Jeff Kleeman, Ellen DeGeneres, Scott Ellis; co-executive producers, Nastaran Dibai, Gregg Mettler, Vanessa McCarthy; producer, Jay Kleckner; director, Ellis; writer, Feldman; camera, Gregg Heschong; production designer, Glenda Rovello; editors, Noel Rogers, Kirk Benson; casting, Julie Ashton-Barson. <strong>30 MIN.</strong>
  • Cast: Elisha Cuthbert, Nick Zano, Kelly Brook, Rebecca Corry, Chris Williams, Brandon Mychal Smith