Although Harold Pinter’s second play has been recognised as a “lost” treasure – it was written in 1958, put aside and first produced at Hampstead Theatre in 1980 – Ian Rickson’s production at the National still carries considerable shock value.

This black comic tale of life, death and torture in a repressive state institution around Christmas time is weirdly prophetic. Pinter had volunteered as a “guinea pig” at the Maudsley Hospital and received electric shock treatment. How might such “treatment” be deployed in the wrong hands?

In The Hothouse, we see the institution’s lock-tester, Lamb (Leo Bill), losing confidence in his job, then his mind, before having his brains fried in a soundproof room. The boss, Roote (Stephen Moore), is pondering the death of one prisoner and the birth of an unexpected child to another. There are discrepancies. It's also snowing. The building itself is echoing with sighs and groans (and a cheerless jazz score, between scenes, by Stephen Warbeck). Hildegard Bechtler’s boldly stage-filling design reeks of the 1950s with its functional furniture, white-tiled corridors and wooden-framed windows.

Roote has some strange military status and is indeed deferentially referred to as “Colonel” by the head porter Tubb (Henry Woolf), who might be a rapist – most of the staff had relations with the pregnant woman, we are told - and is certainly a crawling spokesperson for the under staff downstairs.

The only woman we see is another staff member, Miss Cutts, whom Lia Williams embodies with a dreamy, dislocated sensuality. She plays table tennis with colleagues and is no stranger to Roote’s bed. Other monosyllabically named employees – Finbar Lynch’s saturnine, manipulative Gibbs and Paul Ritter’s hilariously floppy-haired Lush – jostle for position. A coda recaps on a massacre in a government office surreally decorated in white curtains, manned by Lobb (Peter Pacey).

Apart from being terrifying, the play is very funny, with comic non-sequiturs and idiomatic riffs that show Pinter gelling his Kafkaesque side with his Peter Cook revue style. The Hothouse is a comedy about authoritarianism and its puppet masters. It has also clearly been influential on playwrights like Sarah Kane and Martin McDonagh.

Rickson, making his NT debut, allows the play to meander a little in its own rawness, no bad thing. Moore’s Roote, for instance, is far less threatening than either Derek Newark in the first production or indeed Pinter himself in the 1995 West End revival.

Moore’s sing-song delivery and distracted air make his random cruelty and psychotic unpredictability all the more disturbing. And his Churchillian Christmas message – honouring the men who sacrificed themselves in the War so that we might continue – has a wonderfully hollow ring now we know all about incarceration units from the Gulag to Guantanamo Bay.

- Michael Coveney