The title character in Mister Johnson, Bruce Beresford’s colonial drama, is a smilingly cheery Nigerian clerk (Maynard Eziashi) who sports a pith helmet and a cream-colored three-piece suit and considers himself, in spirit, a true Englishman. Mister Johnson is precocious and eager, and he’s an expert at charming the British officials who have come to West Africa to expand their empire. Yet he doesn’t make enough money to support his relatively cushy life-style (which includes a beautiful African wife whom he has purchased, on a kind of monthly lease basis, from the neighboring tribe). And so he steals from the coffers of his white employer, the decent, stolid district officer Harry Rudbeck (Pierce Brosnan). The movie is about how Johnson dooms himself by attempting to straddle two worlds. Beresford, adapting Joyce Cary’s 1939 novel, looks at the psychological relationships inherent in colonialism with some subtlety. The British are racist but human; only one of them, played by a bellicose Edward Woodward, takes any sort of mean-spirited pleasure in his power. Johnson, the invisible scoundrel, is never quite as innocent as he seems. Yet when you come right down to it, he’s still pretty innocent. Eziashi plays him with such a relentless, singsong inscrutability that by the end of the movie, he veers uncomfortably close to becoming a liberal-humanist Stepin Fetchit.