At first, it feels like a narrative layer too far. Bertolt Brecht'swarning against dictatorship, which casts Hitler as Al Capone and borrows liberally from Shakespeare, is here relocated to a generic, corrupt African state.

Zimbabwean actor Lucian Msamati'sArturo Ui stands for all the continent's autocrats, not just his own country's latest defiler, Robert Mugabe. David Farr's production therefore feels overburdened and attenuated at first, only to pick up remarkably, in terms of atmosphere and resonance, in the second half.

Theoretically, Ui's early beginnings as a "gangster", terrorising small businesses with his quasi-military gang, should chime well with what we know of Africa's warlords. But Brecht's heavy irony - "two months without a murder, a man's forgotten" - and arch language sound clunking.

The historical parallels are forced and the staging, on a set of golden sand and upended vegetable crates, is uninspired. Msamati looks the part, stocky and pugnaciously bald, accessorising his military dress jacket with bling and a string vest over a barrel paunch. But he and the rest of the nine-strong cast are hesitant.

What a difference an interval makes. The second half 's show trials, assassinations and annexations of territory have obvious Nazi roots but they come to embody the nightmarish unreality of life in any dictatorship.

Translator Ralph Manheim loosens Brecht's didactic grip a little. Music adds a darkly funny edge, the lighting becomes more expressive and effective. Ti Green's set wakes up, with a florist's doorway becoming a rival's coffin, and the podium from which Ui implicates us, the audience, in his rise. Even the gunshots that herald Ui's every appearance seem less glib and more sinister.

Above all, Msamati seems like a different actor. He grows in presence, eloquence and depth, especially in his Richard III-style wooing of his murdered rival's aghast widow, and in the polar emotional extremes provoked by his Banquo-esque sidekick, Roma (the forceful Ariyon Bakare). Above all, he shows us what Brecht intended, that a dictator's rise is only partly due to ambition and greed, and mostly due to opportunity. It's a comeback better than most dictators manage.

• Until 15 March (0871 221 1729).