On paper, Giant Leap sounds compelling.  Bringing together a handful of well-known stand-up comedians, it takes an iconic moment – Neil Armstrong's first step on the moon – and looks at it from an unusual angle, asking who exactly penned the immortal words about the small step for man and giant leap for mankind.  Unfortunately, despite the obvious potential of the concept, the script is over-long and convoluted; the result is neither a convincing piece of theatre, nor a successful vehicle for its stars' comedic talents.

Perhaps inevitably, the Moon Landing of the play is being faked on a Hollywood sound stage – although when you think about it carefully, you realise that's almost completely incidental to the plot.  The most attention-grabbing among a varied array of characters is Phil Nicol's self-obsessed, manipulative film producer, who promises the world to those around him but will surely prove the most unreliable of allies.  The acting honours, though, belong to Tom Stade, who cuts a believable and likeable figure as a washed-up film director; cast out during the McCarthy era, he's now living a life of cynical decadence while secretly yearning for a way back to success.

Lewis Schaffer, meanwhile, does a lot of the heavy lifting, providing a constant stream of one-liners which helps keep up both the interest and the laugh count.  He arguably has the easiest role – he's a comedian playing a comedian – but his theatrical stage-craft is good, and he knows how to be integral to a scene without stealing it.

The same can't be said of the army liaison officer, who's very good at standing to attention in the audience's sight-lines but not so impressive when it comes to capturing the arrogance and imperiousness of high command.  The producer's young assistant is a forgettable character, who doesn't entirely justify his inclusion in the script; and though the oh-so-perceptive secretary sitting in the middle of the room is a well-drawn and likeable figure, her role in the conclusion of the story is far too easy to predict.

You'll have picked up from that run-down that there are a lot of characters in Giant Leap, and therein lies part of the problem.  It's just too busy on the stage: we don't learn enough about anyone to develop much empathy, yet only Phil Nichol's swaggering producer is extreme enough to work as a comedy stereotype alone.  Towards the end of the play, an odd excursion onto the theme of civil rights is politically commendable, but it needs to be woven much more tightly into the whole of the storyline if it's not to seem like an afterthought.

And there were far too many stumbles on the day I attended – though we could count that as a meta-joke, since the play ends with a rather confusing argument over whether Armstrong did or didn't fluff his momentous line.  When all's said and done, I spent most of the 75 minutes longing for the next witty intervention from Lewis Schaffer, which rather poses the question of why I didn't just go and see his regular stand-up show.  Overall then, despite strong and contrasting performances from Schaffer, Stade and Nichol, this small step into theatre seems unlikely to herald a giant leap into new thespian careers.