River of Smoke, By Amitav Ghosh

In autumn 1838, Bahram Modi, one of Bombay's most profitable traders, puts together "possibly the single most valuable cargo ever carried out of the Indian subcontinent". Discreetly stowing thousands of chests of opium in his hold, Bahram sails for Canton where, in defiance of the Chinese authorities, opium has been smuggled into the country for decades. Fifteen prior sorties have steadily built up Bahram's wealth, while a long affair with the hostess of a kitchen boat has led to a son.

That son is just one of a number of subtle subplots in the novel, which include a Cornish gardener charged with acquiring Chinese species for Kew Gardens. Accompanying him is Paulette, an orphan who, besotted by a mulatto sailor, flees the home of her benefactor, Mr Burnham, a bombastic British merchant in Calcutta. Burnham soon fetches up in Canton with his own cargo of opium and a pompous belief that free trade is "as immutable as God's commandments". But Neel Rattan is also there – a Calcuttan aristocrat bankrupted by Burnham, jailed, transported and presumed dead. He is now working incognito as Bahram's scribe.

Even before coming to the main drama, Ghosh has in place this rich background of complex loyalties and antipathies among his polyglot cast. It's a background that is Dickensian in both its scope and tone. Effete young artist Robin Chinnery captures much of this colour in missives regaling Paulette with Canton news. Chinnery's gossipy asides offset the increasingly sombre turn of events when a reputedly incorruptible new governor is sent from Beijing to stamp out Canton's opium traffic.

The triumph of this satisfyingly long novel – the second in Ghosh's Ibis trilogy, about the Opium Wars, that began with 2008's Sea of Poppies – is Ghosh's underpinning of the vivid characters, brio and adventure of the Canton trade with the moral gravity of the foreign merchants' hypocrisy. Imperial brinkmanship steadily ratchets up the novel's pace. By establishing Bahram as his principal actor, Ghosh is able to triangulate the self-interest of the British community from the perspective of an outsider. The result is an enthralling yarn, swollen with minor stories but increasingly resonant in its moral clarity. History suggests the trilogy's final episode will offer further reversals; but in Ghosh's fluent pen the sense of outrage will surely remain.