Marital discord and suburban disaffection are not new subjects for director Sam Mendes, who rose to prominence with 1999's deservedly Oscar-winning "American Beauty." Indeed, were it not for its distinct inferiority, "Revolutionary Road" would make for an ideal companion piece. Extremely well-acted and not without its effective interludes, Mendes' latest effort is done in by a final ten minutes that lessen the story's would-be impact with an overload of tacked-on contrivance. Furthermore, the awkward concluding moments would be better suited for a derivative horror-thriller along the lines of "The Stepford Wives." They have no place in this film.

The screenplay by Justin Haythe (2004's "The Clearing"), based on Richard Yates' novel, so jarringly drops the viewer into the middle of the trials and travails of married couple Frank (Leonardo DiCaprio) and April Wheeler (Kate Winslet) that one wonders for a while if the reels are out of order. April, once an aspiring actress who has settled for a mediocre regional play put on at the local high school, walks out of the performance fragile and disappointed. When Frank tries to talk to her about it on the drive home, an argument erupts between them. Gradually, the Wheelers' lives come into focus. They have two young children, they live in a faceless 1950s Connecticut suburb, and while Frank trods off to work in the city each day to a job he has no passion for, April sadly whiles away her hours as a homemaker.

When April suggests that they escape their mundane existence and move to Paris to start fresh, Frank's initial skepticism over the idea quickly turns to anticipation. Finally, April will be able to go to work and make something of herself while Frank figures out what he wants to do with his future. Their relationship sparks to life as plans are made to move in the autumn. As the summer months tick by, however, unanticipated happenings and a case of cold feet on Frank's part slowly but surely put a wrench in their chance for escape.

Disagreements. Hurtful screaming matches. Affairs on the side. A husband and wife disenfranchised and suffocated by the lives they have built for themselves. This describes "Revolutionary Road" in a nutshell, and the same themes were dealt with in a more affecting manner in 2004's "We Don't Live Here Anymore." For much of its running time, "Revolutionary Road" is searing and involving, deliberately paced but with an underlying tension that keeps the viewer invested in the relationship between Frank and April. We want Frank and April to follow through with their plans to move to Paris, just as we shrink down in our seats waiting for the next shoe to drop. Drop, it does, culminating in a fiery confrontation so wrenching that the nerves jangle.

Onscreen together for the first time since 1997's "Titanic," Leonardo DiCaprio (2008's "Body of Lies") and Kate Winslet (2006's "Little Children") are dramatic powerhouses as Frank and April. DiCaprio embodies Frank with constant guilt--guilt over the affair he has been having with office worker Maureen (Zoe Kazan), guilt over the idea of leaving a company where his late father worked his whole life--parlayed by a stubbornness that keeps April from being able to convince him of the limitless options set out before them. Winslet is exceptional as April, a woman desperate to flee from the societal conformity of the 1950s and recapture the passion and zest she once held. As her hopes for a brighter tomorrow slip away, April's distraught feelings can be read without Winslet having to utter a syllable. Together, DiCaprio and Winslet share an undeniable chemistry even as the characters they play grow all the more insufferable to one another.

In supporting turns, Kathy Bates (2007's "P.S. I Love You") is strong as neighborhood busybody Helen Givings, while Kathryn Hahn (2008's "Step Brothers") leaves a lasting impression as April's neighbor friend Milly. Both Helen and Milly have prescribed to a brand of subservience that is at direct odds with April's way of thinking, and yet both mask their own forms of unspoken loneliness. Most impressive of all within the ensemble is Michael Shannon (2007's "Bug"), unspeakably haunting as Helen's grown son John, a mental patient who, ironically enough, is actually more logical and sane than everyone else around him. While Helen chalks up John's bitter honesty to his illness, April sees him as the only person who notices the paper-thin facade of their lives and truly understands her misery. Shannon buries himself into the intense role and emerges with one of the best, sure-to-be-overlooked performances of the year.

As "Revolutionary Road" approaches the finish line, director Sam Mendes oversteps his boundaries and aims for too much when less would have been more. There is a very finite ending to Frank's and Helen's story, one that is subtle yet powerful, suggestive and meaningful. Had the film gone to end credits at this point, with a certain character standing on a doorstep before walking inside, it would have made for an exquisite capper. Instead, Mendes pushes forward with an additional ten minutes that feel woefully unconvincing. By the time the real ending arrives, the picture has gone to dishonest, confused places that leave the viewer unsure of what the point was. "Revolutionary Road" is better than this cheap finale gives it credit for, and it severely puts a damper on all that has come before it.