One night in 2002, the British public turned on their televisions to find a half-naked man making a death-defying, 28-foot leap between two tall buildings, all in the name of a new advertising campaign for BBC1.
The punchline was that the man was rushing home to watch the telly; to get there, he raced across rooftops, performing a series of spectacular stunts.
In an age of computer-generated effects, the ad might not have seemed particularly extraordinary.
Except, the stunts were real.
The man was a French performer called David Belle, and the ad provided the British public's first introduction to the discipline Belle had helped create: parkour.
I had my first taste of parkour some years later, with the release of the James Bond film Casino Royale. The first minutes of the film feature Daniel Craig, as Bond, chasing an international terrorist through a multi-storey building site. There are the usual stunts, but in between, there are moments of incredible, and graceful, athleticism by the fleeing terrorist.
The actor is Sébastien Foucan, a co-creator of parkour (and the associated extreme sport, freerunning).
In Britain, the key moment for parkour came with the showing of 2003 Channel 4 documentary called Jump London, which set Foucan and some fellow travellers loose in the capital.
Irish actor Alister O'Loughlin was at home in Brighton watching telly with some of his theatre pals that night, and was awestruck by what he saw.
(Try and picture people backflipping off two-storey buildings; if that defeats you, look up parkour, freerunning, Foucan or Belle on YouTube.)
The next morning, O'Loughlin led his group of thespians to the local skate park, where they started trying to run up walls, and generally do things that most people consider not simply insane, but impossible.
Across Britain, thousands of youths were doing the same. But O'Loughlin and co were likely the only theatre company doing it. And they're doing it still. Parkour can be breathtaking, and performing it must be exhilarating. But O'Loughlin found in it something more: a close echo of the philosophy of performance that was emerging within the theatre company he had co-founded, Prodigal.
To look at Prodigal's theatre work, this seems counter-intuitive. One of their flagship shows, The Tragedian Trilogy, is a one-man performance by O'Loughlin dedicated to capturing the essence of the 19th century Shakespearian actor (and one of the greatest, ever), Edmund Kean.
And the show they bring to Dublin's Helix Theatre next week, Caruso and the Quake, is another one-man play, portraying the early 20th century Italian tenor, Enrico Caruso.
A serious bunch of people. So what are they doing throwing themselves around in makeshift adult playgrounds?
The answer lies, perhaps, in that theatrical Holy Grail, 'truth'. By definition, actors pretend; but many perceive the abandonment of pretence as the highest state of their art. They seek to be 'in the moment' -- to respond honestly and immediately to their fellow actors on stage.
O'Loughlin had spent years working with a Serbian theatre ensemble, only leaving when forced to by the NATO bombing of Belgrade in 1999. He recognised in parkour some of the rigorous physical training that had underpinned his earlier experience, and also something of the 'truth' that he coveted.
"Parkour deals with the real, completely. There's no 'fake' in it.
"If you try to climb over a wall, you either get over it or you don't. You can't 'act' your way over it."
Prodigal set about developing a variant of parkour for performance, resulting in The Urban Playground project, in which they both perform their own, carefully-choreographed parkour shows, and train local kids in the discipline (it is particularly effective with disaffected youth).
And at the same time, they continue to work on more conventional theatrical work, combining the physical skills refined through parkour with the kind of text-based storytelling more typical of theatre. In this, they celebrate an old tradition, one in which there were fewer barriers between disciplines (acting, music, dance, storytelling).
O'Loughlin, whose father is from Co Clare, is hoping to tour Ireland in the near future with The Tragedian Trilogy (I saw it at the Dublin Fringe Festival some years ago; it is superb).
More immediately, Caruso and the Quake arrives at the Helix tomorrow week, followed by performances on February 11 at the Mill in Dundrum, and on Saturday 12 at the Watergate in Kilkenny. (For other dates see carusoandthequake.wordpress.com.)
Starring Ignacio Jarquin as Caruso, this is the story of how the great tenor found himself caught up in the San Francisco earthquake of 1906. His fame meant nothing to the elements and he became, like everyone else, a desperate, fleeing refugee.
Clearly the tenor could have done with some free-running skills; instead, he had to rely on his legendary charm.
It is not, O'Loughlin quickly points out, a "greatest hits". Jarquin is a professional singer, but the company strove to make this gripping as a play, not merely a recital.
"When he does, finally, sing, it's worth waiting for," says O'Loughlin.