Hangmen, Wyndham's Theatre

Just what constitutes reasonable behaviour in an enlightened society? Not long ago, the death penalty fell under that umbrella in Britain, and state-sanctioned killing as punishment for the crime of, well, killing is just the kind of twisted irony that cries out for the Martin McDonagh treatment. Here it is, ending the playwright’s 10-year absence from the London stage, and his Royal Court hit fully earns its West End transfer.

We begin in 1963 with a comically botched hanging. James Hennessy (evoking the controversially executed James Hanratty) protests his innocence and has the gall to demand a more famous hangman: Albert Pierrepoint. “I’m just as good as bloody Pierrepoint!” snarls David Morrissey’s Harry Wade (real-life inspiration Harry Allen). He’s rattled, not by the killing of a man who might not be guilty, but by the besmirching of his professional honour. Two years later, hanging is abolished and Wade – at 233 bodies, falling agonisingly short of his rival – is out of a job.

The challenges to identity and self-worth posed by a changing world, and the queasy tension between real and invented, form the backbone of this gripping piece. At the Oldham pub (pictured above) where Wade trades off his celebrity, pulling in punters morbidly fascinated by his past, McDonagh also interrogates the flimsy separation of civilisation and brutality. There’s both calculated and offhand viciousness in the group’s exchanges – the casual racism, sexism, homophobia, xenophobia – and one can menace another without raising a fist. The Pinter comparisons are inescapable, but the play teems with fascinating echoes: a dash of Orton, Tarantino, Fawlty Towers. It’s a high-wire tonal balancing act superbly managed by Matthew Dunster, and his excellent cast breathe life into what could be merely a pastiche with cracking un-PC one-liners.

The tour-de-force performance comes from Johnny Flynn (pictured below) as mysterious Southerner Mooney, the cocky agent of chaos who challenges Wade’s supremacy. Is he the manifestation of Hennessy’s curse, the instrument of bloody revenge, a bully, a murderer, or merely a prosaic prankster? Through the exhilarating U-turns, it becomes clear that truth is less important than how he’s perceived, and what kind of response that warrants. The idea of capital punishment as both reliable, objective justice and effective deterrent is shown to be dangerously absurd, and its abolition does not signal an instant cultural shift. Violence is inherent, and change is glacial – Oldham isn’t exactly in the grip of the Swinging Sixties, at least not in that sense. Didacticism occasionally dictates too heavily, but, at its best, potent political drama emerges from the superlative meeting of farce and thriller.

Morrissey’s Wade is gruff, proud and woefully hypocritical, but this wannabe giant is cowed instantly by the truly imposing Pierrepoint (the marvellous John Hodgkinson). Sally Rogers as Wade’s tough-talking wife Alice and Bronwyn James as his “mopey” daughter fight back against the male cabal, which is really more pathetic than oppressive – Tony Hirst’s hapless alcoholic, Simon Rouse’s semi-deaf codger, Craig Parkinson’s mordant policeman, and Andy Nyman’s former assistant hangman, defined by one ill-judged comment about a criminal’s abnormally large privates. Wade might not take life professionally anymore, but he certainly sponsors their waste of it.

Anna Fleischle’s spectacular multi-level set whisks away a dismal prison cell to reveal the brown time warp of a pub, trapped in a fog of cigarette smoke. It’s as visually precise as McDonagh’s exquisite semantic dissection. Never has the difference between “vaguely” and “definitely” promised – and delivered – such a rousing denouement.

• Hangmen at Wyndham’s Theatre until 5 March 2016

@mkmswain