Less than the sum of its parts, “The Return of Jezebel James” (7 p.m. Fox), sinks under the weight of its contrived plot and impressive pedigree.

“James” offers independent-film fixture Parker Posey a starring sitcom role. It marks the return of the wonderful “Six Feet Under” star Lauren Ambrose and comes from Amy Sherman-Palladino and Daniel Palladino, the creative team behind “Gilmore Girls.”

Posey plays Sarah Tompkins, an uptight editor for a major New York publisher who gets a wake-up call from her biological clock sometime between browbeating her assistant and micromanaging the office caterer to buy the perfect pink cupcakes.

After deciding to become a single mother by any means necessary, Sarah is informed by her doctor that she cannot conceive. Clearly a woman who won’t take “no” for an answer, she searches for a surrogate and finds her long-estranged younger sister, Coco (Lauren Ambrose).

At first, the free-spirited Coco expresses disgust at Sarah’s suggestion. But after a quick montage of her downscale sleeping arrangements, she decides that money and a cozy bed in Sarah’s guest room might be just the thing.

To call this arrangement uncomfortable is the understatement of the year. “Gilmore Girls” soared with witty banter between a mother and daughter so close they could be sisters. This show presents two sisters so distant that they can only contemplate friendship (not to mention motherhood) through a thicket of legal paperwork and overt bribery.

“Jezebel” was clearly written as a vehicle for Posey to show off her well-honed talent for playing brittle, unhinged yuppies. Her “Busy Bee” tirade in “Best in Show” is a classic of its kind. But the emphasis on Sarah’s imperious neurosis leaves little room for Coco’s character development. And this reduces their relationship to a mean-spirited collision of ugly stereotypes.

Just as Sarah’s character depicts professional women as unloving and literally sterile, Coco the surrogate is shown as irresponsible, lazy and scheming – a slacker slob and a mercenary uterus for hire.

The lack of chemistry between the sisters is just the beginning. In the first two episodes, a father character shows up once and is never seen again. Did the girls ever have a mother? Sarah shows near disinterest in her boyfriend (Scott Cohen). He is utterly thrown by Sarah’s sudden maternal urges and by the fact that she treats impending motherhood as no big deal. He may be a cipher, but he’s the only one whose instincts seem remotely human. His befuddlement speaks for us all.

This may be Posey’s first sitcom, but the 1995 comedy “Party Girl,” one of her first notable independent-film roles, inspired a sitcom that ran on Fox for three weeks in September 1996. I will be surprised if “Jezebel James” lasts that long.

Tonight’s other highlights

¢ Sci Fi offers fans a chance to catch up on four episodes of “Jericho” (7 p.m. through midnight, Sci Fi).

¢ Melinda meets a young girl who may share her gift for gabbing with the departed on “Ghost Whisperer” (8 p.m., CBS).

¢ Scheduled on “20/20” (ABC): medical mysteries (8 p.m.), the age of consent (9 p.m.).