By Lisa Schwarzbaum
Updated September 24, 1999 at 04:00 AM EDT

In Guinevere, a wobbly colt of a young woman named Harper Sloane (Sarah Polley) embarks on a transformative romance with a much older man named Connie Fitzpatrick (Stephen Rea). The relationship awakens her, consumes her, teaches her; it also rescues her from the claustrophobia of home, where Harper’s mother (Jean Smart), starved for sexual attention, can barely contain her bitterness while Harper’s father (Francis Guinan) barely contains his obsession with his older daughter (Emily Procter). And when the affair does end, Harper’s life isn’t in shreds, and she doesn’t punish Connie. She appreciates him for who he is, and recognizes him for what he isn’t.

At a time when so many aging male actors are eagerly teaming up — for no good plot-driven reason — with much younger female costars, this patient, perceptive, nonjudgmental love story ABOUT age difference is the first to convincingly explain the temporal physics of May-December romances. That writer-director Audrey Wells (who wrote ”The Truth About Cats & Dogs”) promotes the feminine point of view makes this incisive romantic drama all the more valuable. It’s the truth about men and girls.

Twenty-year-old Polley, a study in intensity masked by poses of languor, inhabits the part with cool ease. (Harper’s fit of giggles as Connie initiates her into sex — he’s done this before, chivalrously christening each young woman in homage to Sir Lancelot’s mistress — flaunts a truthfulness rare in on-screen seduction.) But a good part of ”Guinevere”’s strength also comes from Wells’ ability to imbue Connie with his own malleable dignity, finely fleshed out by Rea. A charming, drink-prone Irishman who lives a cap-A Artist’s life but makes his money as a wedding photographer, Connie’s a Pygmalion seen in all of his potency and pathos.

In a speech that ought to win Smart an Oscar nod, mother confronts daughter’s lover: ”What do you have against women your own age?” she asks, before unleashing a devastating monologue on behalf of women Michael Douglas’ age, and Harrison Ford’s age, and Sean Connery’s age everywhere.

But the filmmaker also makes a fascinatingly unlikely foot fault: At one point, all the women who were ever Guinevere gather to honor Connie, and each other. Who was minding the Round Table when this fantasy of sisterhood bound by fondness for a shared lover was hatched? In a movie so invigorated by realism, it’s a reverie right out of ”8 1/2.”