Based on a true story, 'The Walk' follows the ambition of a Frenchman planning to walk a tightrope between the Trade Centre buildings in New York.
My heart is racing, I am starting to feel breathless, and light-headedness is threatening to overwhelm me.
Convinced I am about to faint, I shut my eyes to block out the terrifying scenes playing out before me on a towering IMAX cinema screen.
But it's no good - I can still hear what's going on, and it is too easy to imagine the horrors being depicted. I take off my 3D spectacles, hoping that will help. It doesn't. I put them back on and tell myself to stop being such a drip. Come on, Walters, it's a film, nothing more than special effects!
That attempt to hang on lasts minutes - until my body tells me I have to leave. I grab my coat and stagger out, clutching onto a handrail. My legs feel like jelly and it takes me 30 minutes to regain my composure.
So what have I been watching? A gory, violent horror film?
No, it is a film with the most anodyne title possible - The Walk. It tells the true story of Frenchman Philippe Petit, who, in August 1974, walked across a tightrope suspended from the tops of the Twin Towers of the World Trade Centre in New York.
It is the realistic depiction of that illegal stunt - a 45- minute walk at 1,350ft, depicted by a swooping camera, with the Manhattan pavements horribly far below - that has brought about my attack of acrophobia, or fear of heights.
But before you think I'm a wet blanket, I can defend myself with the knowledge I am not the only person to have found The Walk unwatchable.
Last week, it was reported that audiences felt nauseous. One posted on Twitter: "Reports of guys vomiting in the men's room post The Walk: True. Witnessed it/came close. Bad visual trigger for vertigo sufferers."
The film's producer, Robert Zemeckis, appears to be delighted. "The goal was to evoke the feeling of vertigo," he said. "We worked really hard to put those audiences up on those towers and on the wire."
Well Mr Zemeckis, you have succeeded. I'd recommend the film has a health warning, perhaps coupled with some members of St John Ambulance on standby in the foyer.
The nauseating recreation of the stunt does raise one question: what sort of man could have performed that feat?
At the time of the walk, Philippe Petit was 25, although he had been planning it since he was 17, when he had seen a picture of the Twin Towers in a magazine at a dentist's waiting room. Petit held a firm belief he had to achieve what many thought was impossible. Although a gifted juggler, mime artist, rock climber, conjuror - and indeed tightrope walker - Petit knew traversing the 140ft gap between the towers would require something special.
That something consisted of single-minded determination and a large dollop of obsessive narcissism - qualities The Walk reveals that Petit, now 66, had in abundance.
Seeing himself as a "rebel poet", he was a non-conformist. By the age of 17, he had been expelled from five schools, and his strict father, a pilot in the French Air Force, had thrown him out of home.
While the Towers were constructed in the early Seventies, Petit started to wow the world with what he called his artistic "coups".
A scene from The Walk starring Joseph Gordon-Levitt as Philippe Petite.
In June 1971, Petit walked a wire suspended between the towers of the Notre Dame cathedral in Paris. Shortly afterwards, he repeated the same stunt by walking between the 300ft pylons that support the Sydney Harbour Bridge.
To help him, he enlisted the services of his girlfriend, Annie Alix, and childhood friend Jean-Louis Blondeau. In January 1974, the team travelled to Manhattan, where he first set eyes on the Twin Towers.
"The minute I got out of the subway, climbed the steps and looked up at them, I knew it was impossible," he recalled. "That's when I said to myself: 'Let's start working.'"
For several months, Petit organised his coup with the same attention to detail as a jewel thief. To reconnoitre the roofs of the towers, he would pose as an architect, journalist and photographer. He noted every detail of the buildings and established where to anchor his wire and cables.
One of the team's biggest challenges was getting the wire from one tower to the other. Weighing a quarter of a ton, it was impossible to throw across.
Eventually, Jean-Louis came up with the solution. He would attach fishing line to an arrow, which he would then fire across the gap using a bow. The fishing line would be attached to a series of successively thicker ropes, which could be pulled over.
Finally, on August 6, 1974, the team launched their coup. Jean-Louis and a young American called Alan Welner entered the north tower disguised as architects, while Petit, another American called David Forman, and fellow Frenchman Jean-Francois Heckel, posed as workmen to enter the south tower.
It took the entire night to get the wire - secreted in a wooden packing case and taken up in a lift - into place. The team on the south tower were almost caught by a security guard and had to hide under tarpaulin, sitting on a beam over a 1,300ft lift shaft.
Finally, at 6am, Petit was ready to step into the void - wearing no safety line. All he had to steady himself against the turbulent winds was an eight-metre pole.
"I had to make a decision to shift my weight from one foot on the building to the foot on the wire," he said. "It would probably be the end of my life to step on that wire, but something I could not resist was calling me."
Soon, a huge crowd - including police - gathered as Petit crossed the wire eight times. He even lay down on it. I found these scenes the most nauseating to watch.
But the moments that saw me almost pass out was when Petit - played by U.S. actor Joseph Gordon-Levitt - steps onto the wire. The camera sweeps above his head and looks down as he makes his way across.
The computer-generated image is utterly convincing - you really feel as if you are there, 110 stories above Manhattan, and just seconds away from a false step, a gust of wind ... and oblivion.
I tried watching the first crossing, but I had to leave. Police let Petit have his fun, then threatened to use a helicopter to pluck him off the wire. He stepped back onto the south tower and was arrested. He was charged with trespass and disorderly conduct, but authorities said the charges would be dropped if he put on a show for New York's children. He agreed.
As he left the police station, Petit found himself being embraced by a woman called Jackie, who told him she wanted to be "the first citizen to personally congratulate me".
And so while he should have been celebrating his triumph with Annie, he bedded Jackie.
But perhaps conventional morality cannot apply to a man who achieved something superhuman that day. Petit was one of those few people who not only talked the talk, but walked the walk.
