Farewell to the Theatre, Hampstead Theatre, LondonA Provincial Life, Sherman Cymru, Cardiff Going Dark, Young Vic, Clare Studio, London

A poignant and subtle new play lifts the lid on a theatrical revolutionary who lost his way

Harley Granville-Barker played a vital role in revolutionising British theatre in the early years of the last century. As a young actor-manager, dramatist and director he ran the Royal Court, championed George Bernard Shaw, and revitalised Shakespeare's plays, stripping them of Victorian clutter and grandiosity.

In Richard Nelson's new play, Farewell to the Theatre, Granville-Barker is embodied by Ben Chaplin. But this is no standard biodrama-by-numbers, for the play alludes only glancingly to HG-B's triumphs. Directed with exquisite acumen by Roger Michell, it's more like a group portrait by Chekhov – melancholy, though not without humour and restorative hope.

Farewell finds Granville-Barker, in 1916, in provincial Massachusetts. With no professional foothold now, he is cash-strapped and lodging as a guest lecturer near the college campus in Williamstown. While maintaining a debonair manner and a wry wit, under the surface he is in crisis, disillusioned with the theatre industry, separated from his actress-wife Lillah McCarthy (more acrimoniously than he likes to admit), and distressed by news of his compatriots back in Europe dying in the trenches.

Gathering in the dining-room of the boarding house are other English expats, lecturing for the drama department too, mostly acting cheery, but quietly desperate – realising they've lost sight of what they once adored, personally and professionally. Tara Fitzgerald's Beatrice, bored by her socially inept husband, is having an affair with a student. Jason Watkins's jobbing Frank has a worryingly frail wife, left at home while he tours. Jemma Redgrave's Dorothy, mournfully dressed in black, has dwindled into a housekeeper and fears her brother, an assistant professor (Louis Hilyer), is about to be ridiculed by his superiors, as he attempts to realise his rookie dream of staging Twelfth Night.

In a less finessed production, Farewell to the Theatre could seem underdeveloped. And those who prefer their drama with more action may well complain that Michell's premiere is anti-theatrical. But it is deliberately downplayed, really beautifully calibrated. Moreover, the fascination lies in what is and what isn't being said.

Chaplin's portrayal of Harley is full of subtle ambiguities: arrogance and tenderness, nonchalance and suppressed loneliness. Redgrave's mix of nerves and bruising frankness is startling, as is Watkins's raw grief, between his tweedy joviality. Talking into the night, seated at long refectory tables that recede into the shadows (radically low-lit by Rick Fisher), this is a poignant study of isolation and intimacy, impenetrability yet also collective sympathy and a rekindling joy in theatre.

A young man kicks against the pricks who run his Russian hometown in A Provincial Life, adapted and directed by Peter Gill from Chekhov's 1896 short story.

Misail (Nicholas Shaw) is the son of a well-to-do architect with mildly august ancestors who, seeing the entire capitalist system as corrupt, determines to toil as a manual labourer, conducting a one-man revolution. As a result, he's ostracised and lives in miserable poverty, until befriended by a bored intellectual, Maria (Alex Clatworthy). They wed, but their dream of becoming beneficent landowners disintegrates.

Gill has skilfully reworked Chek-hov's prose into dialogue, and his staging is choreographically fluid too, on an airily pine-clad stage. Nonetheless, there are longueurs and sudden jumps in the compacted storyline. Crucially, Shaw seemed bland on National Theatre Wales's press night, outshone by Clatworthy; by Lee Haven-Jones as her excitable champagne-socialist chum, Blagovo; and beyond that, by the glitzy £6m redevelopment of Cardiff's Sherman Theatre – complete with curvaceously vaulted foyer and silvery external cladding.

Meanwhile, adventurous theatre-goers are cramming into what is virtually a black-curtained cubby hole for Going Dark, written by Hattie Naylor in collaboration with the immersive theatre company Sound&Fury. This chamber production is, in part, a sequence of mini-Planetarium lectures. John Mackay, in a superb solo performance, plays Max, an astrophysicist who explains the vastness of the universe and the formation of matter with thrilling lucidity, an overhead projector scattering the Milky Way on a canopy above us and across his face as he speaks.

In between these lessons, we see him happily working at home, a devoted single parent with a sweetly precocious little boy whom we never see, only hear in ghostly surround-sound, chattering about outer space. The tragedy is that Max is losing his peripheral vision, suffering from retinitis pigmentosa and Charles Bonnet Syndrome – in which the brain conjures up terrifying hallucinations. He will soon be totally blind, and everything for him – and us – is going dark. Epic and intimate, scientifically fascinating, poetic and heartbreaking.

'Farewell to the Theatre' (020-7722 9301) to 7 Apr; 'A Provincial Life' (029-2064 6900) to 17 Mar; 'Going Dark' (020-7922 2922) to 24 Mar

Theatre choice

Absent Friends, Alan Ayckbourn's 1970s portrait of jaded marriages and lost dreams, is both poignant and comic at London's Harold Pinter Theatre (to 14 Apr). Last chance to see Filter's A Midsummer Night's Dream – delightfully silly, insightful and sexy, with rock band and youth appeal, at the Lyric Hammersmith, London (to Sat).