Like a Ken Dodd show, Robert Lepage's new epic is a feast of fun and a challenge to the kidneys, running at two and a half hours without a break and daring the audience to give in before the end.

Being Lepage of course, the fun side of things is a little muted, even though this strange interwoven narrative is set in glittering, garish Las Vegas and there is an underpinning element of gambling, show girls and weird sex in hotel bedrooms.

Spades is the first in a series of four plays, each one conceived around one suit in a deck of cards. And each show is developed in what Lepage calls concentric circles, his brief handed down from the "360 degree network" of round theatres across the world, from the US to Denmark, France, Italy, Croatia, Spain and the Netherlands.

So, starting with the image of a card table, the figure of a genie-like card sharp, and the idea that, in the military world, "spades" is a substitute word for "swords,"  Lepage and his six amazingly hard-working actors have devised a story set on the edge of the desert just as the US invade Iraq in 2003.

This story involves, at varying degrees of intensity, a brutalised solider (there's a training camp nearby); a strangely at-odds young couple whom we first see being married by an Elvis impersonator; British actor Tony Guilfoyle as a television executive attempting to hawk programmes and cure an addiction; hotel and bar staff, including an illegal immigrant; and the card sharp casting a demonic spell.

All are gradually sucked into a vortex of despair. Poor old Guilfoyle somehow ends up distraught and bare-bottom naked striding through a desert storm (though the effects went awry on opening night). The couple are split apart by the offer of a ticket to a Celine Dion concert and an unwanted pregnancy, while one chambermaid is left lamenting her menopause and another bestrides the soldier in a sexual fantasy sequence he both seeks and abhors.

As usual in burgeoning Lepage, the work is almost painfully "in progress" but still resonates in retrospect with a sort of terrible beauty. It's as if the director has gone round the hardest way possible to come up with a Las Vegas collaboration between Sam Shepard and Robert Altman. It needs a bit more spice and flavour in the writing.

Endemic to the circular story is the circular setting, a big revolving drum which belches amazing eye-level scenic set-ups of bars, gambling dens, bedrooms, a swimming pool and collapsible doors. Video footage and use of screens is for once minimal. Instead, there's a non-stop theatrical bravura to the presentation, its fluency occasionally undermined by the complicated work involved.

That work happens out of sight and underground, so that, after the actors have taken their call, they give way to the real heroes, the stage management staff, who pop up through their own hatches like a tribe of black shirt Mussolini moles who made the cues come on time.