Man on Wire, the odds-on favourite to win the Oscar for documentary today, is exactly that. It may have earned only US$3 million at the box office (actually good business for a documentary), but it seems everyone who has seen it liked it.

On the critical aggregator, RottenTomatoes.com, the film received a perfect 100 per cent rating. That is, of the 137 major critics surveyed, not one of them gave Man on Wire a negative review. In 10 years of Rotten Tomatoes, only Pixar's Toy Story 2 achieved the same perfect score.

Man on Wire, directed by James Marsh, is about tightrope walker Philippe Petit and his 1974 mission to walk on a rope between the World Trade Center towers.

Petit, a charismatic Frenchman, had a burning ambition - before the towers were even fully built - to tightrope walk from one to the other. Man on Wire follows his retelling of the event and its unlikely execution.

appreciate the courage

"It's very hard not to like what Philippe did even if the film doesn't quite work for you," said Marsh in a recent interview. "You'd have to try really hard not to appreciate the courage and the audacity and the beauty of what he created.

"If you don't like that, you're not quite alive in the way that you should be."

That Man on Wire would be so riveting and entertaining wasn't always so self-evident. The Sundance Film Festival nearly didn't accept it, though it was later picked up for US distribution by Magnolia Pictures after it won the audience award and grand jury prize at the festival last winter.

"It was pretty hard to convince people - particularly in America - that this film could work and be viable," said Marsh. "On one level, it's a man walking around on a tightrope, but it isn't that. It's a story about the limits of what we're capable of as human beings."

There were limitations to the filmmaking, though. The setting, obviously, no longer exists. And no video of Petit's actual act was shot.

Instead, Marsh employs "every cinematic resource you could use" to illustrate the tale. Working in tandem with the interviews are recreated scenes, photographs and various video from before and after the stunt.

gripping heist

"I always like to be a movie first and a documentary second," said Marsh. "The process by which he gets there I saw as a kind of gripping heist film. You hope the audience will kind of go with you on that ride, too."

For best documentary feature, Man on Wire is up against the firsthand Hurricane Katrina account, Trouble the Water, Werner Herzog's Antarctica trip Encounters at the End of the World, The Garden - about a South Central Los Angeles community garden - and The Betrayal, which follows the lives of a Laos family after the Vietnam War.

An Oxford graduate and former researcher for the BBC, Marsh has previously documented subjects including the murder of Marvin Gaye, the eating habits of Elvis Presley and the Velvet Underground's John Cale.

In 1999, he made a dramatised documentary called Wisconsin Death Trip about a small town in Wisconsin that suffered an outbreak of murder, suicide and insanity in the 1890s. His 2005 fictional film, The King, starred Gael Garcia Bernal and William Hurt.

But Man on Wire has been his breakthrough. He credits its success to Petit's exhilarating feat: "The nearest thing to a miracle that you can have without divine intervention."

"On one level, it's a man walking around on a tightrope, but it isn't that. It's a story about the limits of what we're capable of as human beings."