Staring down a sheer precipice into a deep abyss with your head spinning, every fibre in your body tries to resist the edge. Meet the men and women who don't. Overcoming their fears, they step off into thin air and fly like birds, hurtling at impossible speeds and gliding across beautiful rolling landscapes. A startling, adrenaline-filled insight into the revolutionary new sport that brings the dream of human flight alive.

At first you might mistake it for a mountaintop costume party: three young hikers in flapping, brightly-coloured bat costumes, pausing to admire the view. But under their faintly ridiculous trappings, Matt, Ellen and Mike are deadly serious. They are wingsuit basejumpers – diehard members of an elite sporting community. Prior to flinging themselves into the void, they've made lengthy calculations, and are prepared to make split-second decisions once airborne. While standing, walking or at rest, their wings hang heavy and uncomfortable from the human body. But in mid-air they seem to morph into a new species and leave the human race behind. In the words of one basejumper: "it's only when you leave the cliff - when you're flying - that you really feel at home."

The very idea of human flight is one of our deepest sources of fear and desire. As old as the oldest myths, it's become a pop cultural motif, recurring in movies and comics from Star Wars to Superman. Throughout history, self-styled "birdmen" have been flying in the face of danger: to men like Otto Lilienthal, Clem Sohn and Leo Valentin (all of whom met their deaths this way) the high risk of fatal accident was "a small sacrifice". Today, however, technological advances mean that the modern-day Icarus is increasingly likely to survive the plunge. And as wingsuits become more comfortable and cheaper to make, the sport looks set for a popularity explosion. A new wave of thrill-seekers is taking to its sewing machines, creating skin-tight flying machines in the hope of taking to the skies.

Written and directed by one of the crazy few, Birdmen tells the story of our attempts to defy the limits of our bodies, via a collage of fantastic aerial camerawork that captures the world's most spectacular scenery from impossible angles. "Few other people understand the feelings involved," says Ellen. It's life-changing, and instantly addictive - but, as with all addictions, the feeling comes at a cost. At 100mph, even clipping a treetop can mean the end. But according to the initiated, that moment of freefall lasts "longer than any other moment in your life" - a feeling that transforms their perception of death. This incredible film is probably the closest most of us will ever get to experiencing it...