The theatrical trailer for "The Pursuit of Happyness" makes the film look like a pandering, sermonizing, altogether been-there-done-that sapfest about a single father struggling to make ends meet for the welfare of himself and his child. The motion picture proper isn't any of those things, or at least does such a good job that the story never wanders into staleness. In fact, "The Pursuit of Happyness" is a rare breed—an honest-to-goodness inspiring slice-of-life that earns every bit of inspiration it holds and never once makes the viewer want to gouge their eyes out. It's based on a true story—what isn't these days?—and told with a preference for stark, sometimes uncomfortable realism over easy contrivances.

Chris Gardner (Will Smith) is a down-on-his-luck guy too unsuccessful at life in general to even be considered a ne'er-do-well. He spends his days going around to hospitals and medical centers in the hopes of selling machines that test bone density, an enterprise that he has sunk a lot of money into and seen very little in return profits. Behind on their bills and with no light at the end of the tunnel in sight, Chris and 5-year-old son Christopher (Jaden Christopher Syre Smith) find themselves abandoned by worn-out and fed-up wife and mother Linda (Thandie Newton). Suddenly left alone to fend for themselves, Chris and Christopher sink further into poverty, losing their house and eventually being forced to stay at a homeless shelter. Chris' single hope to turn things around is a long shot, but one he is willing to take: a non-paying internship at a stock brokerage company with a slim one-in-twenty chance of leading to a permanent, well-paying position.

"The Pursuit of Happyness," which gets the latter part of its name from incorrectly-spelled graffiti written on the wall outside Christopher's day care center, is a veritable charmer. If placed in the wrong hands, its story could have easily become sweepingly maudlin or, worse, no better than a bad Lifetime television movie. Under the assured guidance of Italian director Gabriele Muccino (making his English-language debut) and screenwriter Steve Conrad (2005's "The Weather Man"), it is a moving and heartfelt character-based drama with an unsentimental tone that makes the machinations of the plot all the more urgent and effective.

This is Will Smith's (2005's "Hitch") film to carry, and he does it stunningly. Simply put, his performance is transformative—one of the best acting turns of the year—and deserves to be a real career-turner for a man who has mostly made his living playing loud, wisecracking jokesters. As the put-upon Chris Gardner, it takes all of two minutes to forget the usual Will Smith persona and fully accept him as this wounded, largely interior character whose dreams never seem to reach fruition. Chris is the kind of person in which little seems to go in his favor, and the audience is placed right next to him on the screen, suffering through every humiliation and road block he is made to endure on his path to the happiness of the title.

When, for example, Chris is arrested for unpaid parking tickets on the eve of an important job interview and must attend it with dirty clothes and a paint-splattered face, there is an air of torturous discomfort and genuine suspense in not knowing how the company bigwigs are going to react. Smith is also wonderful in the scenes where he has to carry around the bulky, 40-pound bone density scanners wherever he goes, knowing better than to expect that he will be able to sell any of them. Lightly comic moments squeak through now and again, as when Chris has no choice but to skip out on paying cab fare and is chased down by the irate driver, but the sparse laughs come naturally out of the humanity of the situations.

As young son Christopher, Jaden Christopher Syre Smith is a precocious scene-stealer. Smith is cute without being sugary and wholly believable in the more dramatic sequences where he has difficulty understanding why they can't have their old home back. That he is Will's real-life son only adds to the truth of these characters' pivotal relationship; there is a close, loving and sincere bond between them that can't be faked.

Where "The Pursuit of Happyness" is destined to end up is far from shocking. The story developments are predictable from start to finish, but the scrupulous, multilayered details on the way to this foregone conclusion are what director Gabriele Muccino excels at. In addition, the writing is sharp and authentically three-dimensional; the characters, including a biting but touching Thandie Newton (2005's "Crash") as Chris' coldly downtrodden wife, Linda, may be flawed but are never sidelined by rote shortcuts in their conception; and the carefully orchestrated music score by Andrea Guerra (2004's "Hotel Rwanda") is lovely in its complimenting subtlety. As for the late scene where Chris' hard work finally begins to pay off, it is a cathartic, uplifting moment because the viewer knows how much Chris deserves it. "The Pursuit of Happyness" is, indeed, a happy late-year surprise.