There’s something thrilling about watching a great artist dangle on the precipice of a cliff, walking the razor’s edge between sublime and ridiculous. Fiona Shaw is such an artist. An actress of fierce conviction and commanding presence, I expect it would be mesmerizing to watch her read from the phone book, such is the power of her craft in plumbing the depths of truth out of even the most banal material. Fear not Broadway’s Walter Kerr Theater, mind you, where there is no need to worry about the quality of the writing being strained. Playwright Colm Toibin, whose elegiac novels revolving on themes of personal identity rank among some of my favorite, has fashioned a demanding, intelligent play out of the twinned myths of religion and fantasy. The Last Testament of Mary is no gnostic gospel, but it does imagine the later life of the Blessed Virgin as a woman in self-imposed exile. Mary does not believe that her son was the son of God and furthermore she refuses to co-operate with those simpletons – the writers of the gospels – who insist on visiting her. Mary is a mother, first and foremost, who had the misfortune to have a son who let things go to his head. It is the mother’s paradox for her to simultaneously grieve his death yet curse his megalomania, which turned the unforgiving spotlight of iconography on herself. This Mary wants none of it. And if she were left alone on a bare stage to tell us her story, we would sit enrapt. Yet director Deborah Warner, whose often visionary collaborations with Ms. Shaw stretch for more than a quarter century, will have none of that. For ninety minutes this Mary is a ceaselessly fidgety fuss bucket: moving a chair here, an amphora there, forever arranging then rearranging props and tables with an unlit cigarette dangling from her mouth. If the action is meant to underscore some greater emotional reality it’s not entirely convincing. In fact, Mary’s vulnerability is at its most ferocious when words become too much and the inability to communicate vents itself through the painful stomping of her feet, like a child caught in a tantrum. Designer Tom Pye is complicit with Ms. Warner, littering the stage with enough detritus – not to mention symbolism – to keep an actor busy for two plays, let alone the single act which makes up this evening. It’s too on the nose: the barbed wire, the ladder, the tree which dangles from the sky, its roots not touching the earth. We can’t help but be riveted by Ms. Shaw, who commits to her character so completely that even an act of gratuitous nudity does not take us out of the world of the play. Yet it’s the viewer’s paradox to both applaud the fearless conviction of an artist and wish someone had the good sense to leave her well enough alone.