No one could say that prolific British director Michael Winterbottom does not accept formidable challenges. His new film, the only British entrant in the competition section at Cannes, was shot largely in Karachi, Pakistan, where there were considerable fears for the safety of Westerners working there.

The fears were compounded by the fact that the film is about the kidnapping and gruesome death of Daniel Pearl, the Jewish South Asian bureau chief for the Wall Street Journal who was researching a story on shoe bomber Richard Reid.

The title A Mighty Heart is taken from the book by his journalist wife Mariane who was pregnant at the time, and the film is largely from her point of view. The fact that she is played by Angelina Jolie might have seemed like a compromise. But Jolie tries for as unstarry a performance as possible, even though when she has her son Adam after a difficult birth, there's not a hair of her head out of place.

What distinguishes the film, in which Dan Futterman, Oscarnominated for his work as a writer on Capote, plays Pearl and Indian superstar Irfan Khan is the head of the Pakistani investigating team, is the way Winterbottom portrays the teaming, chaotic city of Karachi, largely with Marcel Zyskind, his cinematographer using a hand-held digital video camera. It seems small wonder that the authorities, at first convinced that India had a hand in Pearl's disappearance, could not find the journalist until too late when a video appeared of his beheading.

Winterbottom does not show us either the kidnapping nor Pearl's incarceration and death but concentrates instead on the bravery of Mariane, a seasoned international journalist, who never gave up until faced with the incontrovertible evidence of her husband's death, and who showed a generosity of spirit towards Pakistan afterwards.

That seems to be the purpose of a film which can become confusing at times as the five harrowing weeks of the search, amid escalating media frenzy, progressed. As confused, perhaps, as the investigation itself following up leads that led nowhere.