You've got to applaud the audacity. Tom Stoppard and André Previn's 1977 play deploys a complete orchestra and the full force of Stoppard's wit to explore the plight of Russian dissidents who were then being locked up in mental hospitals.

The NT's polished 2009 revival, directed by Tom Morris and Felix Barrett with the Southbank Sinfonia, is now back for an encore.

Last time around, critics found the play admirable but politically dated. I think its potent depiction of repression is pretty timeless, symbolically if not literally.

But though the music and dialogue are equally sophisticated and pleasing, they don't always mesh: it's often glaringly obvious that the idea for the orchestra came first, and the play and the politics were built around it.

Adrian Schiller is Alexander Ivanov, the activist banged up with a schizophrenic (Julian Bleach) who shares his name, and who hears an imaginary orchestra in his head.

The fact that their doctor/re-educator is also a concert violinist expands the potential for misunderstanding and multi-layered jokes. The sane man must pretend to be mad, etc

Schiller goes for outright pathos while Bleach gives a coarse-grained portrayal of growling, staring lunacy.

Morris, Barrett and conductor Simon Over orchestrate proceedings smoothly, adding dancers to mime scenes of state brutality.

Altogether, it feels like worthy curiosity that leaves you impressed but also convinced that cost alone did not prevent orchestral, political plays from taking off as a genre.

Until 17 February. Information: 020 7452 3000, www.nationaltheatre.org.uk.