Since appearing on the cover of Time magazine at the age of 14 under the heading “Hollywood Whiz Kids,” Diane Lane has enjoyed a steady film career. Steady but not outstanding.

She’s found leading parts in major films that didn’t live up to commercial expectations (“The Cotton Club,” “The Outsiders”) and starred in blockbusters where her thankless roles were merely window dressing (“A Perfect Storm”). Now in her late 30s, the New York-bred actress has spent the last few years playing moms and schoolteachers in lackluster pictures (“Hardball,” “The Glass House”) that didn’t capitalize on her many talents.

Diane Lane, left, stars as an affluent New York housewife whose affair causes repercussions with her husband (Richard Gere) and family in Unfaithful.

“Unfaithful” may change all that.

While the movie is an effective “ethical thriller” about the perils of adultery, Lane herself is something of a revelation. Down to earth but erotic, fiercely intelligent but morally conflicted, she delivers a devastating performance one that could possibly land her an Oscar nomination next February.

Lane plays Connie Sumner, an affluent homemaker who shares her life with husband Edward (Richard Gere) and son Charlie (Erik Per Sullivan). While running errands one day, a random collision introduces her to Paul (Olivier Martinez), a young Frenchman who invites her up to his SoHo loft. Charmed by the man, she returns to visit him frequently, gradually setting in motion an affair that is doomed to disaster.

While establishing a believable family dynamic between the Sumners, “Unfaithful” manages to build the kind of smoldering sexual tension between Connie and Paul that only happens in the movies. With her earthy prettiness and WASPish demeanor, Lane effortlessly shifts between soccer mom and sexpot depending on the situation. Despite the physicality presented, the movie never crosses over into “Red Shoe Diaries” territory. It’s still more concerned with examining the conscience than the libido.

Her scenes opposite Gere (a maturing actor who is often underrated) find the right tone of a loving marriage that is dulled by complacency. In the film’s opening that portrays a typical family morning, Connie glimpses her husband’s rumpled shirt and tells him, “You’re inside out.” It’s a line that sums up where his emotions are headed. It’s interesting also how he endearingly refers to her as “Con,” a word that implies deceit.

	ReviewRating: *(R)language, violence, sexual content, nudity2 hours, 5 minutesSouthwind Twelve, 3433 Iowa

As with the cultural benchmark “Fatal Attraction,” director Adrian Lyne again crafts a cautionary tale against adultery and the nature of guilt. Lyne manages to extract the most out of seemingly mundane images. In a stark opening sequence showing a child’s bicycle being knocked over by a breeze as wind chimes cry out in alarm, the filmmaker finds a way to mirror the tension of the characters.

Especially intriguing is how Lyne (or editor Anne V. Coates) depicts the initial Connie/Paul coupling. After their first kiss, the scene cuts to Connie’s ride back on the train. As her face relives the tawdry event, flashbacks of the more physical details are interjected. The moment is played for all it’s worth in the expressions and body language of Lane. It’s difficult at times to discern if she’s laughing or crying it’s probably a little of both.

Much of the material is hardly revolutionary (the triangular setup is superficially comparable to “A Perfect Murder,” and the entire project is a remake of the 1969 flick “La Femme Infidele”). Yet the performances and commitment to moral ambiguity distinguish “Unfaithful” from similar pictures.

The ending is particularly brave. And while it may polarize audiences expecting some BIG FINALE, it presents the most likely scenario considering the circumstances of these individuals. As with other sins, people are more prone to try to escape the consequences of their actions than to confront them.