The National Theatre keeps returning to Georg Büchner’s thrilling 1835 drama of the French Revolution – Michael Grandage's NT debut production is the third after Jonathan Miller’s (in 1971) and Peter Gill’s (in 1982) – without ever quite nailing the hectic mix of rhetoric and Expressionism.

Büchner, who wrote the play aged 21 in just five weeks, captures the squall and confusion of the First Terror in the turmoil of street violence, courtroom denunciations and the arraignment of Danton and his friends who are pleading for an end to the executions now running at two dozen a day.

The vivacity of all this is suggested by the fact that Danton, played with great vim and swagger by Toby Stephens, is the victim of the tribunal he founded a few months earlier. Stephens cuts a more romantic figure than did Brian Cox in the last production, though Cox was sweatier, and he embodies the contradictory, impulsive side of Danton to perfection.

But the public street scenes are damagingly cut – the tumult of tarts and pimps, and a foul-mouthed stage prompter called Simon – and the play distilled, almost, in the triangular revolutionary statements of Danton, Elliot Levey’s icy but furtively troubled Robespierre and Alec Newman’s Saint-Just, a red-coated Beethoven lookalike.

The National Assembly is woefully under-populated, too, with a dozen members rhubarbing away upstage while the great debate is joined. There are a few torches now and then, and Paule Constable’s lighting of Christopher Oram’s bleak, high-windowed set, using about half the stage, is a masterpiece of invention: the tribunal scenes look like the paintings of Jacques-Louis David, and Danton’s walk in open country is done by flooding the forestage in sunny rays.

Nonetheless, Grandage’s reductive approach is a waste of the Olivier’s epic potential, although the second half of this compressed version, with its dreams and nightmares and strange, jagged poetry – all very well done in Howard Brenton’s new translation from a literal version by his wife Jane Fry and the Propeller actor Simon Scardifield – is much better.

The early invented scene of Robespierre being assisted in his levée by three women is not a success, and the ingenious sleight-of-hand lavished on the climactic executions at a matchbox-sized guillotine frankly risible. The play needs to breathe again in the last public scene, which is cut.

Barnaby Kay gives another fine performance as Camille Desmoulins, and Eleanor Matsuura caches the eye as Danton’s prostitute. And there’s some classy revolutionary rumbling on the soundtrack by Adam Cork, another example, though, of how aesthetic niceties have disguised the play’s real mess and fervour.