The central idea of "Pay It Forward" is this: Do something to help three people. Something hard. Something they could not do for themselves. Then tell each recipient that, instead of paying you back, he or she should go out and help three other people. As more and more individuals "pay it forward," the acts of kindness will build exponentially, creating a more benign Earth.

It's a wonderful idea, a noble idea; one that I (along with many others, I suspect) intend to put into practice. Unfortunately, when writer Catherine Ryan Hyde decided to turn her idea into a book, she apparently felt our cynical culture would not accept such a sweet concept unless it was couched in ugliness, pain and sacrifice. So she laid the melodrama on thick, creating a tearjerker that turned the central character into the Jesus Christ of New Age spirituality. Her strategy worked and the novel was a hit. Now comes the movie.

"Pay It Forward," the film, has the best of intentions. The cast is outstanding and the production contains quite a few effective sequences. But the movie suffers from Mimi Leder's ham-handed direction, a script that takes the novel's disparate subplots and ties them into a too-tidy bow, and a climactic visual shamelessly ripped-off from "Field of Dreams."

The main story follows seventh-grader Trevor McKinney (Haley Joel Osment), a latch-key kid living in a run-down Las Vegas neighborhood with his mother, Arlene (Helen Hunt), an alcoholic working two jobs to support the family. At the beginning of the school year, Trevor's new social studies teacher, Eugene Simonet (Kevin Spacey), presents the class with an extra-credit challenge: "Think of an idea to change our world – and put it into action."

Trevor takes the assignment seriously and comes up with the pay it forward concept. To test his theory, he offers shelter and some money to Jerry (James Caviezel), a homeless drug addict. When a startled Arlene encounters Trevor's new friend, she storms to the school, furious that a teacher would give her child such a dangerous assignment. There she meets the utterly mystified Simonet, a fastidious, well-spoken creature of habit with a badly scarred face and a guarded demeanor. Thus begins a tentative relationship between the two damaged souls, with Trevor paying it forward by playing matchmaker.

The primary storyline is interwoven with a subplot that begins several months later in Los Angeles, when reporter Chris Chandler (Jay Mohr) is the recipient of a lavish gift from a stranger on a rainy night. Pursuing his benefactor, Chandler learns about the pay it forward idea and decides to trace it back to its origin. A series of vignettes follow, as the investigation gradually leads the writer to Trevor.

Moving the setting of the story from the heartland to Las Vegas was inspired. Where most films focus solely on the glitz of the city's casinos, "Pay It Forward" presents Las Vegas from the residents' point of view, accenting the gulf between working-class folk and the flashy opulence of the buildings that glow in the distance.

Hiring Kevin Spacey, Helen Hunt and Haley Joel Osment was another wise decision. Spacey continues his career path from character actor to mainstream leading man with another carefully etched performance. Hunt also creates a rich, well-drawn character and young Osment is as impressive here as he was in "The Sixth Sense."

Most of the supporting cast must deal with underwritten parts. Angie Dickinson does good work as a bag lady and Jim Caviezel touches the heartstrings as the desperate Jerry, although his doe eyes are played up more than is necessary. In the reporter role, Jay Mohr is serviceable, as is Jon Bon Jovi in a brief appearance as Trevor's wayward father.

Other aspects of the production are less successful. Thomas Newman's otherworldly score is overly reminiscent of his haunting "American Beauty" soundtrack. Continuity problems abound courtesy of the makeup department. Maybe it's the lighting, but Simonet's facial scars appear to change from scene to scene. The same happens with Jerry's teeth, which appear to grow markedly nastier whenever he delivers an angst-filled speech.

But the biggest problems lie in the screenplay and direction. The teacher in the book received his wounds during the Vietnam War. The source of Simonet's injuries (which I won't reveal here) is different, concocted by scriptwriter Leslie Dixon as part of a needless and unwelcome attempt to connect two storylines with an extra level of pain. Her efforts to tidy up the book (watch as a hitchhiking Jerry hops out of a truck and walks onto a bridge, where he immediately encounters a woman preparing to jump) only manage to make the proceedings seem contrived.

As for Mimi Leder, the director needs to take a remedial course in camera work. Beyond a criminal overuse of close-ups, she repeatedly aims her lens at the wrong places. The most egregious offense occurs during a sex scene, when the extremely self-conscious Simonet finally lets down his guard with another person. Leder foolishly elects to show the teacher opening his shirt to reveal his scarred torso. Instead of being entranced by the intimacy between Simonet and his partner, we end up studying the makeup crew's handiwork.

And then there's the ending of the film, which you will find either deeply moving or totally unnecessary. Whether you leave the theater sniffling or angry, I hope you remember that, regardless of its many problems, "Pay It Forward" puts forth an idea that actually could alter this planet. If enough of us are as dedicated and industrious as Trevor, we can take this overwrought, cumbersome fiction and create a better reality.