Grade: D-

As you watch this supposedly sophisticated coming-out comedy from writer-director Sue Kramer, you may just find yourself straining to locate a single line of dialogue that sounds as though it could actually be spoken by a human being. In vain. “Gray Matters” is so utterly synthetic that though set in New York, it might as well be happening on another planet.

The “Gray” of the title is a hyperventilating thirty-something ad exec (Heather Graham) at a firm where she’s struggling to impress a prospective client (Rachel Shelley). She shares an apartment with her brother Sam (Tom Cavanagh), a surgical intern. But they share more than a pad. The two are practically inseparable, so much so that they’re sometimes mistaken for a couple. They even jog and dance together—doing elaborate routines from the old movies they both love. But that’s nothing compared to the ultra-cute conversations they have, with her blithely saying anything that pops into her empty little head and him gamely putting up with it.

The plot kicks in when they meet Charlie (Bridget Moynahan), an attractive woman, during a run in the park, and Sam instantly proposes to her. But when they go to Las Vegas for the wedding, a drunken Charlie kisses Gray, who immediately recognizes that she’s gay. The rest of the picture is about her coming to terms with her “shocking” sexual orientation while working out with Sam that she loves his wife, too.

The premise of the script is bad enough (indeed, the relationship between Gray and Sam—which we’re apparently supposed to find darling—is actually pretty creepy), but it’s made a lot worse by Kramer’s inept plotting and plastic writing, as well as by Graham’s incredibly irritating performance. The poor girl babbles, prances about and jumps up and down in mingled exhilaration and exasperation like some demented version of the young Goldie Hawn, and by an hour in you feel like throttling her. (The nadir certainly comes in the embarrassing, sitcom-quality sequence in which she and Sam accidentally announce to her office that she’s gay, sending her into a paroxysm of embarrassment. Not terribly enlightened. And when a twist at the close brings Gray an unexpected chance at love, you basically doubt she deserves it.)

Cavanagh is less annoying simply because he has less screen time, and Moynahan gets by on her fine physique (which she shows off in revealing lingerie at every opportunity), but Molly Shannon is stridently unfunny as Gray’s office mate and the gifted Sissy Spacek positively wan as her therapist. The only person who adds any honest charm to the proceedings is Alan Cumming as a cabbie who’s—for some inconceivable reason—smitten with Gray. And that’s despite the fact that Kramer makes him play a truly awful drag scene. It makes one cringe.

As does the whole of the movie. Though it’s reasonably well mounted (one of the executive producers, for some reason, is Alexander Payne), “Gray Matters” comes across as so completely misguided that one can only wonder why anybody thought it worthwhile to spend their time and energy making it. Because despite the title, “Gray” doesn’t matter at all.