Harold Pinterís new play, No Mans Land, is about precisely what its title suggests: the sense of being caught in some mysterious limbo between life and death, between a world of brute reality and one of fluid uncertainty. But although plenty of plays, from Sweeny Agonistes to Outward Bound, have tried to pin down that strange sense of reaching into a void, I can think of few that have done so as concretely, funnily and concisely as Pinterís. All Pinterís plays are to some extent about the invasion of territory; and this is no exception. The setting is a curved, opulent room on a summer night in Hampstead. Hirst, a rich, famous belle-lettrist, has invited into his room a shabby, beer-stained poet Spooner, whom he has apparently picked up in Jack Strawís Castle.