In some ways director Katie Mitchell is playing it safe for her first production at the National Theatre since a falling-out with the previous régime a few years ago. She is not engaging in one of her now-trademark deconstructions of a classic work, building a stage experience piece by discrete piece; she is not even staging this piece in her standard crepuscular gloom, although once again she uses only the lighting of the environment shown on the stage, with no “stage lighting” as such. The choice of material, too, is in some ways risk-free: Sarah Kane’s plays seemed outrageous on their premières as recently as the 1990s, but are now firmly ensconced as modern classics.

What Mitchell has done with Cleansed, however, is nothing short of magnificent. She anatomises both the horror and the hunger in Kane’s 1998 play, in which an unspecific “institution” tests the limits of its inmates’ emotional as well as bodily endurance. Kane’s imagery was extravagant: flowers bursting through the floor, no problem, but rats carrying off amputated body parts, more problematic. Mitchell creates a brutal yet inescapable world in which there is quite enough torture and torment to make up for the occasional missing image. The institution is staffed by faceless men, their heads simply black spheroids, who trundle equipment and victims on and off and belabour them in between. They are all but mute; when one speaks, his voice is electronically fluked down in pitch (just as in The Encounter, which I reviewed last week). Graham, the ghost of an earlier victim, speaks in normal range but is given a bass-baritone echo.

Grace, Graham’s sister who enters the institution in search of reminders of him and gradually metamorphoses into him, is kept almost permanently onstage by Mitchell, as if bearing witness to this all-pervasive impossibility of seeing our desire for contact meaningfully realised, or at least only at a devastating price. Michelle Terry, always a compelling actor, is shockingly vulnerable as Grace, as naked psychologically as she is physically. Mitchell even finds music more resonant and disquieting than that which Kane specified, from a child’s rendition of Blondie’s “Picture This” to a track by 1970s American electropunks Suicide… almost a step too far given Kane’s own death, but one more element in this vista of degradation through which a shaft of hope nevertheless shines, at once nobly and stupidly. I cannot imagine a more powerful production of this powerful play.

Written for the Financial Times.