THERE MAY be some people who wish to walk out of Crave. Not because of one of those close-to-the-knuckle acts of sex and violence - an anal rape, say, or a casual dismemberment - that have characterised Sarah Kane's previous work and earned her the thorny crown of new writing's enfant terrible. But because Crave is a 45-minute verbal assault: line after snappy line of thought and feeling so at odds with each other that your responses are pushed to polarities. One minute, it's as though you are been subjected to piercing insight, the next, light-headed nonsense. Although there's not a torture implement in sight, this doesn't make for any easier viewing than Blasted, Cleansed or the Seneca update Phaedra's Love.
The set-up resembles some kind of daytime TV chat show: two men and two women walk on and begin speaking. They are not introduced, although they are named after letters of the alphabet. At first, they appear not to know one another, but gradually details emerge.
There are points when the exchanges seem to indicate mutual understanding, moments when each is in his or her own shell. Kane's extraordinary poetry of desire is delivered with anything from playfulness and indifference to blank despair. Crave can be cringe-making,but it can be exhilarating, too. Above all, it confirms Kane as a uniquely experimental voice.
Runs until 5 Sept (0131-228 1404)