Loitering with intent outside the public lavatories in St James Place may not normally be your idea of fun, but it is well worth joining the queue for this, one of the most darkly intriguing shows on the fringe. Hailing from Ireland, where it was a hit at the Dublin festival and voted the sexiest show (scariest would be more like it), Semper Fi's performance is a play in two halves. The audience is divided: one party is sent first into the ladies' toilets and the other into the gents'. Then there is a short interval (no conferring) and you swap toilets. Essentially, this is two interconnected plays, and only when you have seen both does the whole really make sense.
Set in Ireland in the 1950s, in a murky world of high-class prostitution, political scandal and establishment cover-ups, Ladies and Gents is a visceral little shocker that combines the seediness of the toilet with the clinical chill of the abattoir. Experiencing it is rather like turning over a stone and discovering something so nasty underneath that you want to avert your eyes. That is entirely intended as a compliment.
If this took place in a traditional theatre, it wouldn't amount to anything out of the ordinary. Here, though, it becomes a very clever example of the extent to which location and space play a part in theatre, and how the dislocation of the normal relationship between performers and audience can create a strange alchemy. At the end, you hurry out of the toilets feeling unclean, as if you desperately wanted to wash your hands. This unsettling piece of theatre is so nasty it's nice.
· Until August 23. Box office: 0131-228 1404.
