Athol Fugard likes to dump his characters in settings with no dramatic thrust or tension. A prison yard is a favourite. He specialises in bored, talkative characters who squirt the time away swapping memories and indulging in bursts of creative play-acting. It’s dull to watch but good fun to perform. Thesps love to step out of character and road-test a range of fictional personalities.

‘Master Harold’… and the boys is classic Fugard. We’re in an empty restaurant in South Africa in 1950. Lunch service has ended. Two waiters twiddle away the afternoon discussing sex, ballroom dancing and beating women (as if this were a standard feature of male behaviour). Enter the boss’s school-age son, Hally, whom both waiters know well. Much chitchat and reminiscence follow. The waiters dip into Hally’s school-books and invite him to discuss mathematics, the works of Shakespeare, the historical concept of ‘the man of magnitude’ and other intellectual topics such as the precise definition of art.

Little of this is credible. Hally seems too well-informed for a schoolboy while Sam, the older waiter, can barely read English. Finally we get some excitement. The telephone rings. Sam answers. It’s Hally’s mum calling from the hospital with important news about Hally’s dad. Hally’s dad is slightly better. The call ends. And the three characters resume their scholarly banter.

In the final 15 minutes, hidden tensions break the surface. Hally makes a racist joke and Sam tactfully rebukes him. Hally, cowed by Sam’s reprimand, invokes a social convention that obliges black citizens to address a white male, even a child, as ‘Master’. But will Hally really force this humiliation on his two friends? The play ends with a genuinely inspiring and poetic passage of rhetoric in which kite-flying becomes an emblem for political cooperation and harmony. It’s an amazing climax and Lucian Msamati does well to capture Sam’s nobility and almost Christ-like spiritual grandeur. But the ascent to this dazzling and unexpected peak is a dreadful 90-minute slog.

[BLANK] by Alice Birch calls itself ‘a theatrical provocation’. The show appears to have been inspired by interviews with women who know the justice system inside out. Critics at press night were handed a thumping great tome, 516 pages long, from which two hours of drama had been distilled.

It opens with a dippy Yorkshire mum, Kate, burbling manically about her new boyfriend. The scene is subtle, naturalistic and extremely funny. A drug-addicted prostitute breaks into the room and starts to argue furiously with her mother. What happened to dippy Kate? Eventually it becomes clear that this new scene is unrelated to its predecessor. More set-ups follow. Damaged and addicted women are shown screaming and keening in a variety of prisons, hostels, refuges and therapy centres. Each change of location is signalled ineptly, or not at all. And the shapeless narrative becomes tiresome to fidget through.

Kate returns. The boyfriend turned out to be a wrong’un who poured scalding tea over her. Kate tries to assure her distressed daughter that the nasty man won’t do them any further harm. Then a second comedy gem. A garrulous cop informs a mother that her daughter, Zeinab, has committed suicide but the inept cop keeps talking about her personal troubles rather than tactfully breaking the bad news. This has the feeling of a Pinteresque classic.

Next, a dinner party. Zeinab, who just killed herself, reappears. So the scene must be a flashback. But there’s a puzzle. Zeinab is no longer an angry prostitute but a coke-snorting yuppie who works for Twitter. Are there two Zeinabs? It’s unclear. Zeinab the angry prostitute who is also a yuppie knows dippy Kate who shows up having turned into a lesbian. Kate wants to show off her sexy new lover to Zeinab and her chums. Enter Kate’s daughter. ‘Hi Mum,’ she says, but not to Kate. The daughter is addressing the actress who previously played Zeinab’s mother.

Does that make sense? Probably not. But that statement accurately describes this confusing scene. Doppelgängers are everywhere. There are two Kates, two daughters and two Zeinabs. And in each case, the two characters have the same name and are played by the same actor. How can a theatre make such a lazy blunder? Without external clues, the audience can’t possibly distinguish lesbian Kate from dippy Kate, or angry Zeinab from Zeinab the yuppie.

The dinner-party descends into a chippy rant about bourgeois Londoners snorting coke and indirectly funding knife crime. This finger-wagging speech would be better suited to a sociology seminar. And the entire show has a ‘take-your-medicine’ flavour. A pity. The writing is excellent in places, the naturalistic acting is brilliantly done and the performances are terrific. But the editing is disastrous. A succinct and well-focused drama exists somewhere in this mass of research. A literary ferret should be hired to winkle it out.