Rarely does a documentary film combine nail-biting tension with humour and awe, but Man On Wire does that and more.

The film follows the death-defying stunt of impish French tight-rope artist Philippe Petit and his dare devil aim to navigate, on foot, a single wire stretched between the World Trade Center's twin towers, in 1974.

Dramatisations of Petit's boyhood dream of traversing the towers and his obsessive efforts to realise the stunt are combined with interviews from Petit and his partners in crime to tell a story of jaw-dropping beauty and bravery.

Despite Petit being the first person interviewed in the film, pre-empting the outcome of the stunt, director James Marsh's documentary is as taut as the dare-devil's high-wire.

The regular sight of Petit traversing immense chasms is unnerving but the achievement of the seemingly impossible is inspirational and life-affirming.

But it is the build-up to the actual stunt, with Petit and his band of French and American conspirators trying to evade security and secure the wire across the huge gulf separating the towers, which provides the real tension in the film.

The shocking ease with which Petit and friends are able to breach security at the towers is a chilling reminder of the building's tragic fate.

The 90 minute running time is probably a bit stretched but the dreamy optimism of those who dare to dream can achieve the impossible, will leave a smile on your face and a spring in your step.

Art or madness? Criminal or heroic? These are just some of the questions raised by this hair-raising and awesome documentary film.

But as Petit eloquently answered New York journalists baffled by the reasons behind the stunt, "there is no why".