Redundant, Royal Court, London

Happiness is a side-order of onion rings

Lucy was in all the top classes at school, but not because of academic prowess. She just happened to be sleeping with her form tutor – a married charmer who raped and impregnated her and then abandoned her in their Sheffield council flat along with a young daughter who was later taken into care.

Given that its 17-year-old central character boasts that unenviable CV, you might surmise that Leo Butler's new play would unfold as an indignant drama about victimhood. But that's not how things develop. Redundant – a promising piece that won this year's prestigious George Devine Award – spends far less time wringing its hands over the origins of Lucy's plight than in training a beady dispassionate eye on the abject poverty of culture that allows a girl to collude in her own undoing. While it obviously feels for her, it also manages to find a quirkily outrageous humour in the stuntedness and insensitivity of the world she inhabits.

Proceeding in mordant jump-cuts, whose impact is intensified by explosive snapshot flashes, Dominic Cooke's adroit production pulls off the trick of being utterly unsentimental without ever seeming heartless. Here, literature is the Argos catalogue; self-respect is a new pair of trainers bought by blowing the whole of a week's benefit; happiness is the side-order of onion rings on the double whopper with cheese that is possible on giro day.

Although she seems freakishly uninterested in the daughter she gave up, Lucy evidently feels that the only way of facing the future is by starting a family with someone else. Regrettably, Darren (Simon Trinder), the school friend by whom she becomes pregnant, doesn't want to get trapped. So Lucy's dream of a domestic idyll involves deceiving Wil Johnson's Dave, a black guy twice her age, whose qualifications for the role of paterfamilias aren't best endorsed by the fact that, while she retches and reels through her pregnancy, he and his sleazy sidekick Gonzo (Craig Heaney) blithely use the flat as a crack-smoking den.

There are one or two false notes in the script at those moments where the dialogue descends to the perky ingratiation of lines from a sitcom – as when Lucy's gran (Eileen O'Brien) retreats to the bathroom from some sticky little family summit with the declaration that "I can't believe I missed Watchdog for this".

But Butler knows how to give a shockingly casual comic buoyancy to the political incorrectness of his characters who manage to air unsound views on everything from the benefits of marrying the disabled ("Don't knock it. Know where you stand wi' disabled. Know where their loyalties lie, for one. Long as yer make 'em feel human") to the breast-enhancing effects of pregnancy ("Oooh. 'Ave some of that, mate. None o'yer semi-skinned shite in these bastards").

Lyndsey Marshall is excellent in the central role – tough, vulnerable, arrested and sometimes wrapped in a glow of maddening self-deception that lets you see why this girl would prefer to subject her grandmother to a vicious beating rather than accept a reality-check from her. We leave her at the brink of going on the game for the drug-pushing Gonzo. When she gives birth to a second girl, Lucy bewails the fact that she has added to the family's luckless female line and created more abuse fodder for men. Certainly, if your fate were to be a woman in the society Butler depicts, celibacy or lesbianism would seem unusually attractive options.

To 6 Oct (020-7565 5000)