Richard Gere and Diane Lane play Edward and Connie Sumner, a happily married couple who dote over their young son Charlie (Erik Per Sullivan). Their marriage has no unusual strife or conflict; in fact, they appear to be very successful in their relationship. One afternoon as Connie makes her way down a Soho street, a vicious windstorm kicks up and knocks her into a stranger. He is Paul Martel (Olivier Martinez), a French book dealer who is handsome and exotic. Paul helps Connie pick up her papers and invites her into his apartment, where he gives her bandages for her bloody knee. They engage in some small talk and she leaves, never really expecting to see Paul again. A few days later, she returns with a bottle of champaign as a token of appreciation. They talk and flirt, and Paul more or less makes a move on her. She refuses but can't stop thinking about him, even though she deeply loves Edward. Nevertheless, she returns again to Paul's apartment and a torrid affair begins.

Diane Lane gives an Oscar-worthy performance as Connie. When she first begins having sex with Paul, she is aroused yet crying uncontrollably. "I don't know how to do this," she tells him through tears. It's clear that Connie's lust for Paul is matched only by her guilt over cheating on Edward. That kind of inner conflict is an incredibly difficult thing for an actor to achieve, but Lane pulls it off brilliantly. In her movies, she's usually better than the material and finally she has a role to establish herself as a major actress. She equally nails the other scenes, as Connie engages in more infidelity while dealing with her immense guilt at the same time. She sneaks off for an afternoon of passionate sex with Paul, then returns home to the arms of her loving husband. The script never spells out why she cheats, but it doesn't have to since she doesn't really even know herself. Lane makes her character's motivation a Rohrshach test for the audience; look at her performance and decide for yourself why Connie strays.

Eventually, Edward begins to suspect that something is going on. He hires a private detective to trail Connie. Upon learning that she has been trysting with one Paul Martel, Edward shows up outside the Frenchman's building. He looks up sadly, wondering if his wife is in there with another man. Edward decides to ring the bell. Paul, now aware that he's been caught, allows his lover's husband to come in. Edward looks over and sees the unkempt bed where his wife has recently screwed this stranger. The hearts of the audience break right along with his. For me, this scene was the emotional high point of Unfaithful. It's not a story about why people have affairs; it is about the guilt and shame that haunt everyone associated with them. Gere's performance is every bit as powerful as Lane's for the way it shows the sorrow Edward feels upon learning of the betrayal. I found the movie both sad and disturbing as it examined the devastating impact an affair has on this otherwise happy marriage.

And then...well, I'd better issue that spoiler alert right now. I can't cite my objection to Unfaithful without blowing its major plot twist, so if you don't want to know, stop reading. After consuming a few drinks in Paul's apartment, Edward is overcome with grief and hits Paul over the head with a snow globe, killing him. He then ditches the body in a landfill. At this point, the film stops being about the affair and becomes about the murder. Connie eventually finds out that Paul is dead and that her husband is the killer. The police come around to question the Sumners, and there are lots of scenes designed to make you think that they know Edward is guilty. The couple tries to decide how to handle the situation, since both have done something they feel extremely guilty about. Quite frankly, I didn't care what they chose - this wasn't the part of the movie I was interested in. I wanted to know what happens to this marriage after the infidelity. Does Edward flat-out leave her, or try to make it work because he's so much in love with Connie? How does she deal with her own regret over senselessly ruining such a good marriage? Lyne not only lets the screenplay lose focus, but he also stages everything in that overly glossy, melodramatic style that's become his trademark. For example, when Edward confesses the murder to Connie, Lyne films him in total shadow, just to underline the glaringly obvious.

In its final forty minutes, the film goes completely off track, removing its focus from the affair and placing it on trashier, less believable parts of the plot. It's dispiriting to see a movie begin so intelligently and end up so stupidly. Lyne was on track for a while, delivering a smart, emotional film for adults. Ultimately, though, he didn't trust his instincts and returned to the formulaic fluff he's known for. Connie may have been unfaithful to Edward, but the movie is unfaithful to its own premise. My advice: go for 80 minutes, then walk out.

( 1/2 out of four)

Unfaithful is rated R for sexuality, language and a scene of violence. The running time is 2 hours and 1 minute.