Directed by Fernando Meirelles, starring Ralph Fiennes, Rachel Weisz, Danny Huston, Hubert Koundé, Bill Nighy, Gerard McSorley and Donald Sumpter.

When you've introduced yourself to European audiences with a film as memorable as 'City of God', just how do you follow it up? Make a similar film and get criticised for a lack of adventure? Shoot a straightforward studio film and face accusations of taking the easy way out? Spend so long searching for the right project that you end up over-analysing the one you do choose and dull your creative edge? These were just some of the pitfalls faced by Brazilian director Fernando Meirelles after his 2002 film secured the double glory of worldwide acclaim and popularity. But Meirelles has nothing to fear with 'The Constant Gardener' - he's succeeded in making John le Carré's source novel a complex and deeply moving film, part thriller and part scathing indictment of the West.

Fiennes plays Justin Quayle, a career diplomat in Kenya who has just been told that his activist wife Tessa (Weisz) has been murdered by bandits in the north of the country. While Justin possessed the stiff upper lip aloofness that seemed a pre-requisite for climbing the promotion ladder, Tessa was an idealist and considered by many to be something of a loose cannon, immersing herself in the culture and treating the people as individuals, not statistics. The authorities consider her death an open-and-shut case, but Justin thinks there's far more to it. Why has her travelling partner - a local doctor - not been found? Had Tessa stumbled upon something? And do his employers know more than they're telling him?

To reveal any more of the plot would be to spoil one of the films of the year. In what has been a poor 12 months for thrillers, 'The Constant Gardener' has a superb and urgent storyline which hooks you from the start and will make you think twice about the comfort you're able to return home to after watching it. It's a film that pulls no punches and offers no solutions, but most will leave the cinema a lot wiser than they were when they bought their ticket.

While many directors would just use Africa - probably not shooting there or creating a fictional country- as a backdrop for their film, Meirelles makes it a character, bringing its colour and mystery to the screen in a way which is just as absorbing as the can of worms that Fiennes' character has to open. It's arguable whether a European or American filmmaker could've captured a continent so vividly, but Meirelles and 'City of God' cinematographer César Charlone's work here is so memorable that they're operating on a different level from the rest.

Possessed of a gift that constantly makes you wonder if he's a leading man who's a character actor or a character actor who's become a leading man, Fiennes excels here as Justin Quayle, brilliantly revealing the inner strength and iron will underneath the meek exterior. His relationship with the also excellent Weisz - told in flashbacks - is one of those all too rare examples of great screen chemistry which depicts the nature and stop-start complexity of true love. In a career with more than its share of unforgettable performances, this is up there with Fiennes' best, while the edgier material on offer here shows where Weisz should direct her talents in the future.

This is a film which refuses to play it safe or take the easy way out and will probably reach and inform more people than a year's worth of articles and reports. You owe it to yourself to see it; you owe it to millions of others too.

Harry Guerin