The Crucible is a big play about big themes. It addresses weighty issues such as faith and superstition, collective hysteria and paranoia, the price of integrity, the explosive anarchic power of repressed sexuality, the cost of infidelity, and the way scapegoats serve to maintain social order and bolster shaky notions of piety. Not having seen it before, its reputation as one of the much-studied classics of American theatre preceded it, and so, to be honest, I was expecting an intellectual discourse that would leave me enriched on a mental level, but one where I'd probably have to leave my emotions at home, except possibly for "intrigued".

The beginning met my sombre expectations, and I braced myself for a long, worthy night - although the superb new shape of the auditorium happily banished many dreary memories of feeling disconnected from the Abbey stage. A candle flickered into life in the dark, and we were faced with a grey abstract monolithic box, walls like slabs, and a huge overhanging girder, giving the space an oddly anachronistic industrial-era resonance. I doubt one could create a grimmer, more alienating set. The darkness receded under a horizontal shaft of cold white light, to reveal a body laid out in front of us like a corpse. Men and women, dressed in monochrome, brought a pale semblance of life to the stage, as they fretted about the inexplicably comatose girl, Betty Parris, and what she and her friends had been doing in the woods together the previous night, to leave her in such a state.

The bleakness had a strong effect on me - I found myself starved for colour, for warmth, for signs of vitality, for some relief. The girl's father, Peter Hanly's Reverend Parris, a neurotic ferret of a man overwhelmed by a terror of witchcraft rumours spreading, set the uneasy tone of the times for us: tense, volatile, unhappy. A queasy helplessness dominated, a lack of ability to be rational, grounded, sensible. We heard the story of Ann Putnam, a simple woman failing to make sense of the pain of having had so many of her babies die in her arms, and how she had arrived at her deeply flawed conclusions, that set in train the events that were to destroy so many people's lives. Intense grief can warp our rationality, and once I had connected with that, through Marion O'Dwyer's goosebump-raising performance, it began to be clear how magical thinking could flourish in that community, like a pale and sickly growth mushrooming overnight on rotting wood, and I knew that I was in for a gripping night of theatre.

The frenzied hysteria gathered momentum, and took on a frightening life of its own, and accusations of witchcraft flew around, ensnaring dozens in a cruel double-bind: confess to witchcraft and name others who have walked with the devil, or face a guilty charge, and death. The story became a simple but moving one: how each person struggled to retain their integrity in the face of irrational hate and fear. The Reverend John Hale (Peter Gowen), a witchcraft expert, called in to investigate the girls' disturbing behaviour, led by the manipulative Abigail Williams (Ruth Negga), began by impressing with his calm rationality but he, too, got swept up in the storm, as the cases snowballed and went to trial. A farmer, John Proctor (Declan Conlon) and his wife Elizabeth (Cathy Belton), whose marriage was already frosty due to his having had an affair with Abigail, found that their private troubles became the business of the courts, as they too found themselves accused, and betrayed. Another farmer, the eccentric and wily Giles Corey (played to comic perfection by Tom Hickey), moved heaven and earth to obtain justice for his accused wife.

The simplicity and fluidity of this production by Patrick Mason (even though I saw it at first preview) was deeply impressive, because at every twist and turn the emotions of the characters were available to us and instantly understandable. The audience tittered with nerves when the young girls' collective hysteria was at its most disturbing and creepily infectious. When we heard what unhappy fate befell Giles Corey in the last act, so much had he endeared himself to us, the effect was devastating. The strain in the Proctors' marriage was achingly familiar, and the thaw in their relationship, when it finally came, brought tears to my eyes. John Proctor's character, so flawed and passionate and heroic, is proof alone of Arthur Miller's genius as a playwright, but Conlon and Belton's superb performances brought immediacy and heart to his words.

This was ensemble acting at its best - clear as a bell, accessible, taut, generous, not a weak link in the chain, not a false note struck in the entire evening. It seemed utterly right that the accents were Irish, unforced, natural. By the end of the night, I found myself still hating the mechanical oppressiveness of the set, the accusing, interrogative, blinding light of each scene change, a hint to force us, perhaps, to question our own capacity to be swept away by hysteria. But I liked the fact that there was no reference to the 1950s and the McCarthy era; the psychological truth of The Crucible is timeless. However much as I disliked the greyness of the environment, the humanity of each character seemed even more palpable as a result. This production worked for me because it didn't have an angle, the director had no high-concept axe to grind, his sole interest and achievement was to allow his gifted actors to tell a great story well. Sometimes we need the plainest of settings to enable us to see gems at their sparkling best.