Mark Gevisser's memoir of growing up in Johannesburg opens with a cliffhanger based on two of the scariest words in the South African lexicon (after "apartheid era"): "home invasion", a risky editorial choice, given the reluctance of white liberals in the country to dwell on crime. In this instance the drama, set against Gevisser's loving portrait of the city, is an apt introduction to its history of violence: the author, sitting in an apartment with two friends one evening, is confronted by three armed men who break in and threaten to torture them if they don't hand over everything.
In this scenario, of course, the predominant racial history of South Africa in the last 100 years is inverted so that the victims are white and the aggressors black. But the commonplace nature of a terrifying encounter is a quick and effective route into the life of a city that has, since the 19th century, been characterised by the rough justice of the gold-rush frontier town.
Gevisser, a prominent journalist and biographer of Thabo Mbeki, is acutely aware of the historical ironies in his story, not least because of his own ambiguous identity as the gay son of Jewish Lithuanian immigrants to South Africa. Part memoir, part psychogeography, his book is concerned with life as it's lived in these liminal spaces, which, in Gevisser's fine handling, take on both physical and symbolic dimensions: the title, Dispatcher, is the name given by Gevisser as a child to the nerdy game he invented of poring over his dad's Johannesburg street map and figuring out routes between points.
In 1970s South Africa, this was no straightforward task. The young Gevisser noticed oddities in the map: that there were large, uncharted areas where the Soweto and Alexandra townships should be, part-time homes to his family's housekeepers and which, in the eyes of apartheid officialdom, simply didn't exist. "As it began to dawn on me how bizarre" the map was, "I began to ponder the reasons for its eccentricity. Thus began, cartographically, the dawning of my political consciousness."
Forty years on, and 20 years after South Africa's first democratic elections, much has changed in the city of 11 million people, frequently referred to as the economic powerhouse of Africa and responsible for 17% of the country's GDP. But the lines drawn on the map during the worst years of apartheid will take more than a generation to fade. After "white flight" – or as Gevisser puts it, "downtown Johannesburg's abandonment by big business at the moment when it finally became accessible to all" – the city centre is as divided as ever. It is the project of this fascinating book to chart how the new boundaries relate to the old.
All white South Africans are the descendants of immigrants and the conventional part of the book is a family history that goes back to the Baltic at the close of the 19th century. Gevisser's paternal grandparents came from a small town called Zelva, in modern Lithuania, to which the author returns, to find relatives in the cemetery and familiar names in the dispiriting museum dedicated to the second world war. Those ancestors who stayed behind, along with 90% of Lithuania's Jews, died in the Holocaust.
For the people who left, South Africa was not exactly the promised land. As Gevisser notes, "After the war, the government of Jan Smuts did not allow Jewish refugees from Europe to come to South Africa." Gevisser's father enrolled at the University of Stellenbosch, in the Afrikaner heartland, where on his first day on a botany course the lecturer said: "There's a Jew in my class. Can this be true?" then failed him on principle. That he ultimately befriended the Afrikaners and ended up dating this man's daughter persuaded Gevisser senior both that "Afrikanerdom was not irredeemably racist", and that the only political position to have was "vehemently anti-nationalist and pro-liberal".
Gevisser writes all this knowingly; the position of Jewish South Africans was infinitely more privileged than black South Africans and, by the time Gevisser and his siblings were born, his parents' liberalism was tempered by a reluctance to rock the boat. They were appalled by their son's nascent activism, which, looking back, Gevisser is himself robustly sceptical about. I have yet to read a book that so precisely nails the limitations of the white South African liberal: while the young Gevisser flattered himself that he was a rebel against his parents' conformism and rules, he concedes that "I also thrived within them". The truth about white activism was that, however admirable, "we were wrapped in our magic cloak of whiteness" – the phrase is Hugh Lewin's, from his memoir Stones Against the Mirror. "We could always retreat into our impenetrable privilege … the worst would always happen to them not us."
The separation between "them" and "us" and the civic insanities it gave rise to are well known. Gevisser's gift is to catch the odd moments of more subtle distortion, those which "document the uneasy and sometimes transgressive nature of … apartheid South Africa". For example, in photos of his childhood, "I am struck by the contradictory position often occupied by servants: even though they are incidental – really just there to hold a child to the camera – they are often an image's focal point." Striking too is the extraordinary dynamic of living in a big house while a servant and her children live in what amounts to a shed in the garden. The huge denial becomes the unacknowledged focus of an entire system.
In among these observations is a lot of straightforwardly great writing. When Gevisser and his partner go looking for a flat in the northern suburbs, he is hit by the memory of visiting his grandparents, with "the smell of chicken soup and incontinence". When they decide to get married – a mixed-race couple – he arrives for an initial meeting at the government offices with some trepidation. While South Africa has one of the most liberal constitutions in the world, it is a deeply homophobic society on both sides of the colour divide. In a touching scene, the young black woman issuing the licence briskly lectures him about his rights and tells him off for being so reluctant to have a big wedding. "You have full rights in this new South Africa. You have the right to make a fuss. I think you need to go home and have a very serious chat with your partner." They are married by an older Afrikaner woman, who, despite her habit of referring to heterosexual unions as "normal", plunging Gevisser and his partner into hopeless giggles, is wildly enthusiastic about marrying them.
In the background to all this is the biography of the city around which Gevisser takes long, thoughtful walks; through the old cemetery at Hillbrow; around the mine dumps; up inclines from which one can see the canopy of trees that make Johannesburg look so green from above.
The denouement of the home invasion is horrifying, although, as in most things, it could have been worse. And Gevisser is brutally honest about this, too. For those who have the option of living abroad (Gevisser spends half his time in France), staying in a city like Johannesburg is a choice "to compromise your personal security so as to be able to live a life of comfort and ease dependent on cheap domestic labour". When the intruders broke in, it "ruptured that perimeter of denial that all Joburgers have to erect if they are to sleep comfortably at night."
Nevertheless, one comes away from this book reminded of what a magnificent city Johannesburg is – a fierce, ambitious, global metropolis, sharper than London, more bolshie even than New York. "There is always a corner of optimism in Johannesburg, the promise of vitality, the prospector's dream." Make no mistake: in spite everything, this is a love letter.
• Emma Brockes's She Left Me the Gun, about her South-African born mother, is out in paperback from Penguin. To order Dispatcher for £15.19 with free UK p&p call Guardian book service on 0330 333 6846 or go to guardianbookshop.co.uk.
