Jerusalem, By Patrick Neate

Patrick Neate's rollicking debut introduced 19-year-old Musungu Jim, a wimpish, gap-year Brit teaching English in the fictional mid-African state of Zambawi. Jim's engagement with huge spliffs, an over-sexed witchdoctor and an inept coup d'état was a comic romp given surprising depth by Neate's detailed invention of Zambawian mythology. Twelve Bar Blues, his second novel, transposed the witchdoctor, Jim and "a knackered old whore" called Sylvia to America in search of African roots. Neate's snappy prose swelled with the jazzy rhythms of the Big Easy to deliver a second ribald, hugely satisfying instalment of Zambawian high jinks.

Jerusalem, his compelling fifth novel, is billed as the final instalment to this belatedly-defined trilogy. It's darker and more ambitious, bringing his ruminations on cultural heritage and authenticity into sharper focus.

Jim is back in Zambawi, but dying of Aids, with Sylvia now his wife. They foster children orphaned by Aids, coping with 18 life-hungry kids (and the emotional legacy of many wards who have died already). The witchdoctor is in solitary confinement, raving prophetically, having offered unpalatable advice to the President – whose misrule and posturing against the former colonial powers bring him and his country into close proximity with the very real crises of Zimbabwe.

Despite private woes, Jim and Sylvia have purposeful, substantial lives, in quiet contrast to the Pinner family, whose more selfish antics bring the focus to England and Englishness. Preston Pinner, known as P or Tuppence, left Cambridge with an acute sense of the commercial value of his "intuitive grasp of what was cool". He founds Authenticity, a fashionable and lucrative agency that helps companies to associate their product with the numinous quality of coolness.

Philanderer, alcoholic and P's dad, David Pinner is a Foreign Office minister and shameless opportunist. Sent to Zambawi to negotiate the release of an arrested businessman, he fantasises about his triumphant return; but Neate's deft storytelling allows arrogance and prejudice to pitch him into deliciously Zambawian turmoil.

Jerusalem uses the Pinners to lampoon the vacuities of the PR industry and politics. Neate has plenty of fun with Nobody, P's latest protégé, whose "simultaneously nostalgic and angry" rapped version of Blake's anthemic poem gives an incendiary, immigrant's eye take on British culture. Neate has produced an upbeat entertainment that, unlike its subjects, does manage to probe some essential aspects of morality, character and identity. Witty and acerbic dialogue impel an unflagging comic plot, with Neate confident enough to allow weightier questions to hang in the balance.