Consumed by remorse and despair, a successful businessman gives up all hope after accidentally killing six strangers and his beloved wife. To make amends, he decides to off himself and donate his bodily organs to seven strangers.

That's Seven Pounds in a nutshell, and it sounds more like Saw VI than a holiday drama reuniting Pursuit of Happyness director Gabriele Muccino with Will Smith. But unlike Happyness, the feel-good movie of 2006, Seven Pounds is just the opposite – a feel-bad movie – and its unpleasant aftertaste lingers in your mouth for days. After watching this depression-inducing saga of sadness, you'll need a Zoloft prescription.

Believe it or not, though, the above synopsis doesn't spoil anything because Seven Pounds reveals the main character's suicide in the opening scene. "There's been a suicide," Ben (Will Smith) tells a 911 operator. "Who's the victim?" the operator asks. Ben replies, "Me."

The movie then flashes back, showing Ben – a Los Angeles IRS agent – investigating the moral fibres of several strangers. First, he finds that a local doctor (Tim Kelleher) with health problems abuses patients from time to time. Then, he talks with Ezra Turner (Woody Harrelson), a blind pianist who works as a phone operator at a meat company. There's also a poor Hispanic woman (Elpidia Carrillo) who cannot endure her husband's physical abuse any longer. They all need something from Ben... they just don't know it yet.

Soon, Ben runs into Emily Posa (Rosario Dawson), a lonely woman with a serious heart condition that may kill her unless they find a donor soon. The two hit it off quickly and begin an unexpected romantic fling. At this point, the film transforms from goal-oriented drama to lackadaisical romance. It's a direction that's so different from the first half that it's as if there are two separate movies here. There's a way to blend the contrasting ideas, but Muccino and writer Grant Nieporte miscalculate the transition and find themselves wandering, seemingly without focus or direction.

To the movie's credit, Smith delivers his best performance since Ali. He's come a long way since his Fresh Prince of Bel-Air days, and his maturity as an actor is aptly demonstrated in Seven Pounds. In one of his most emotional roles to date, Smith tackles the drama fearlessly. His performance appears effortless and never feels forced or contrived. He's a breath of fresh air in an otherwise overwrought picture.

But there's a difference between dark, honest dramas, and movies that are just plain downers. The gut-wrenching Hunger, Revolutionary Road and The Wrestler are three recent films – also in some sense about characters who give up – that are much more difficult to watch than Seven Pounds. But those films don't disguise themselves as inspirational dramas. They are pit bulls, not poodles, and they present themselves honestly. This movie has edge, but it wants to be the bastard child of Happyness. It's a razor blade wrapped inside a teddy bear.

Blake French