Harry (Chris Cooper) is a buttoned-down, closed-in respectable type. Richard (Pierce Brosnan) is more easygoing. Harry is painfully earnest as he tells his friend that he plans to leave his wife for a much younger woman. The younger woman truly and deeply loves him. All his wife wants is sex.

Why does Harry share this information? I think he wants understanding and forgiveness from a man he respects. He has arranged for the young woman to join them at lunch. She is Kay (Rachel McAdams). She has the bottle-blond hair and the bright red lipstick, the Monroe look.

She's a sweet kid, and she really does love Harry. The movie has a voice-over narration by Richard, but we don't need it to tell from the look in his eyes that Richard desires Kay, and that from the moment he sees her, he wants to take her away from the dutiful Harry.

How dutiful is Harry? So devoted to his wife that he can't stand the thought of telling her he wants a divorce. He decides to take pity on her, spare her that pain, and murder her instead. Sort of a mercy killing. He knows how devoted his wife is to him, and how this news would shatter her, and he doubts if she could stand it.

This story, which crosses film noir with the look and feel of a Douglas Sirk film, balances between its crime element and its social commentary: Everything Harry does is within the terms of a circa-1950 middle-class suburban marriage, with what we have been taught is all of its horrors.

What about Harry's wife? She is Pat, played by Patricia Clarkson, who is so expert at portraying paragons of patient domestic virtue: so trusting, oblivious or preoccupied that she never thinks to question Harry's absences when he's seeing Kay.

There is so much passion in this story that it's a wonder how damped down it is. Nobody shouts. And we discover that Harry is not the only person in the story who can surprise us. The lesson, I think, is that the French have the right idea, and adultery is no reason to destroy a perfectly functioning marriage.