Ten years ago Rona Munro's play Iron won plaudits and prizes on its premiere. Matt Beresford's production is far from the only subsequent revival of the work, but I imagine as much as any other, it makes the case for this resonant and compelling psychological drama.

The play tells the story of a series of unnervingly taut encounters between 25-year-old Josie (Emma Deegan), a divorced, lonely career woman, hoping to learn about her forgotten childhood, and her mother, Fay (Shuna Shaw), who has served 15 years of a life sentence for killing Josie's father, without ever explaining why.

Fay is reluctant to meet her daughter, but denied even the opportunity to watch post-watershed television she is desperate for any kind of excitement, however vicarious. The ultimate incompatibility of their desires may be clear from the outset, but Murray's sprightly script, eschewing melodrama and sentiment, and with impressively authentic dialogue, keeps the tension high throughout a lengthy running time.

Even so the plot becomes almost irrelevant alongside the extraordinary creation of Fay, a wonderfully exuberant and complicated central character. If Murray began her piece with the ghoulish desire to imagine how a female murderer ("as rare as unicorns" in Fay's own characterisation) ticks - she finishes by creating a rounded portrait of an almost classically tragic figure, whose passion is both her greatest strength and flaw.  

Shuna Snow captures an extraordinary range of emotions as Fay's explosive mixture of charisma, rage, remorse and institutionalised cunning are gradually revealed through her meetings with her daughter. At some point just before the interval, I noticed some of the other actors seemed for a short spell to drop out of character. They weren't themselves speaking at the time, and if anything they were required only to keep aside and react quietly to Fay's speeches. And yet I got the impression they too were possibly as memorised as the audience by Snow's virtuosity as she cartwheeled through conflicting emotional states at breathtaking speed. Bereford's intelligent direction allows Snow to roam the stage whenever we slide into Fay's imagination, an excellent counterpoint to grim static claustrophobia of the meeting room face-offs where mother and daughter are forbidden to touch one another.

Emma Deegan as Josie in her quiet poised performance is a good foil for Snow. Excellent support is also given by Don Cotter and particularly Emma Carter (who, in being unafraid to appear unsympathetic, brings great depth to her part) in their roles as guards. In their suspicion they seem almost as institutionalised as their charges. Yet all their characters inevitably pale beside Fay, and the tension slackens slightly whenever she's absent. The only false note in the production is the occasionally intrusive use of somewhat tinny music, a prop neither the cast nor the writing really requires.

It may not be new but this is probably as good a piece of fringe theatre as you're likely to find in London in this year. Hats off to all involved.

Iron, at Old Red Lion TheatreJimmy Kelly reviews Iron at the Old Red Lion.4