Rumor Has It…

“Rumor Has It…” is a high-concept comedy whose high concept is the most interesting thing about it. Once that’s out of the way, it’s just your basic relationship melodrama.

But it is a great concept. A Pasadena woman named Sarah Huttinger (Jennifer Aniston) comes to realize that her grandmother and mother both slept with the same man, and that their story was subsequently fictionalized into the book and film “The Graduate.” What’s more, she thinks she might be the offspring of the affair between her mother and the man in question.

The film is set in January 1997 (which makes one character’s reference to “Titanic,” released 11 months later, a bad idea), with Sarah newly engaged to her adoring boyfriend Jeff (Mark Ruffalo). They have flown home to Pasadena for the wedding of Sarah’s younger sister, Annie (Mena Suvari), and thus Sarah finds herself once again immersed in the insular, gossipy world of the Pasadena elite. (“That’s what happens when you give people everything they want and leave them alone for 100 years,” someone says by way of explaining the place. Incidentally, the film’s screenwriter, Ted Griffin, was born in Pasadena.)

Sarah, fast developing cold feet about her own engagement, seeks advice from Katharine (Shirley MacLaine), her saucy, hard-drinking, “don’t call me Grandma, it makes me feel old” grandmother. Sarah learns that her now-deceased mother ran off to Mexico a week before her wedding and was discovered to be pregnant just days afterward. Sarah has a father, Earl (Richard Jenkins), whom she loves but has nothing in common with. Is it possible this other guy — the one Mom met in Mexico, the one Grandma also had a fling with, the one played by Dustin Hoffman in “The Graduate” — is her real father?

There’s one way to find out: Spontaneously fly to San Francisco, where the man himself, a technology mogul named Beau Burroughs (Kevin Costner), lives and works. If he’s her father, there are new avenues to be explored. If he isn’t her father, well, he does find her attractive, despite being old enough to be her father. (More or less. In real life, Costner is only 16 years older than Aniston.)

It goes downhill from there. Sarah’s fiancé Jeff grows concerned over her hesitation and possible infidelity, Sarah herself falls into a pit of self-doubt and despair, and Annie — remember Annie? — has an anxiety attack on her honeymoon. It becomes a sullen mess of soap opera emotions, no longer a comedy but some kind of gangly hybrid.

Rob Reiner has directed smooth comedies, from “This Is Spinal Tap” to “The American President,” but this is not one of them. Indeed, while there are high points here and there — Shirley MacLaine spruces up every scene she’s in — in general the film moves ploddingly, with individual scenes that don’t “build,” and an overall story that doesn’t, either. There’s a lot of wasted potential here. And what, Dustin Hoffman couldn’t do a cameo? Come on!

C (1 hr., 36 min.; PG-13, a little profanity, some innuendo.)