"Guinevere" takes your breath away and never lets you have it back.

An extraordinary movie about the love between an older photographer (Stephen Rea) and an impressionable ingenue (Sarah Polley), it seduces you with the cardiovascular pumpety-pump of passion, then applies the death choke of emphysema.

Love -- at least, this love -- starts as the precious domain of the poetic and the chosen. By the end of the story, it's a plunge into the dizzying abyss. You don't scream, though. You can't.

This exciting, ultimately sobering journey starts "Five Years Ago" in San Francisco, when Harper Sloane (Polley), an extremely reluctant bridesmaid at her sister's starched little wedding, looks for the missing photographer.

She gives up the search and grabs a champagne bottle to chug with existential desperation on a back porch. She looks up and there he is: Cornelius "Connie" Fitzpatrick, rumpled, sleepy-eyed, not quite devilishly handsome, but handsome in manner. Old enough to be her father. Squinty, Irish and sexily going to seed.

He uncorks the bottle, while his gentle voice toasts her soul. His romantic vision marks the first time someone has found real value in her. When Harper goes to his apartment -- an almost comically bohemian pad -- to pick up the wedding photos, an unspoken spiritual deal is struck.

Connie wants her to become an artist. She can choose photography, painting or whatever. But she must work at it. And the process should take about five years. Down the road, he says, he can see her leaving him. But for now, it's time to move in and get serious. He calls her Guinevere, for reasons of his own.

Harper is gone. "Guinevere" is born. So is a romance that will consume her completely. She pays no attention to the screeching, soon to be ex-girlfriend who's leaving Connie at the time. Is Harper the next lamb to the slaughter, or the one he'll stay with forever? You think about the odds. You stop thinking about the odds. So does Harper, who becomes Connie's apprentice, setting up lights for his photo shoots and clicking images herself. When Connie tells her to take pictures of a friend suffering through detox in the hospital, Harper balks at the task -- particularly when matters take a turn for the gross.

"You don't take a picture when it looks right," Connie admonishes. "You do it when it hurts so bad, you can't stand it."

"Guinevere," written and directed by Audrey Wells (who wrote "The Truth About Cats and Dogs"), intentionally indulges every cliche and conceit of the artist-ingenue romance, then rakes them over the coals.

At the beginning, we're allowed to enjoy the rhapsody. As Harper, Polley is coltishly alluring. Her eyes are almost willfully innocent. She's unsure -- and yet semiconsciously aware -- of her sexual power. Rea is wonderfully ambiguous as Connie. Their love seems mesmeric, but also suspect. Is Connie abusing her or liberating her? Is his silent worship of Harper authentic or the romantic equivalent of serial murder?

When Harper meets Billie (Gina Gershon), a woman who has clearly "graduated" from Connie's five-year plan, she realizes she isn't the first Guinevere to pass through Connie's casting court.

But after seeing the alternative -- life with mother -- she realizes which world invigorates her more. Is she foolishly clinging to naivete by staying with him, or does she see a truth that has eluded his previous lovers?

The great thing about "Guinevere" is that you can never be completely sure. And even though you know that things surely cannot end well, you maintain a sort of white-knuckled hope for the couple's bliss. You remember the look in Harper's eyes the first time Connie's hands touch her. There is such joy in her face, it seems almost spiritual. And even if everything is delusion, why not fool yourself with love like this?

GUINEVERE (R, 105 minutes) -- Contains obscenity, nudity and sex scenes. At the Cineplex Odeon Dupont Circle.