"Perversely, xenophobia is a product of citizenship, the claiming of a new birthright. Finally, we belong here, and that means that you do not."

This is Jonny Steinberg's comment on a harrowing episode in which Asad Abdullahi, a Somali merchant in a Cape Town township, is attacked in his shop while his customers calmly walk over his prostrate body to loot his goods. In the new South Africa, prosperous Somali merchants become targets of a black majority, now relieved of the oppression of white rule and determined to expunge anyone not of their kin and kind.

Asad, a genius at business, a survivor of civil war in his own land and of grievous losses during peregrinations in Kenya and Ethiopia, is a hero. But Steinberg, a South African prizewinning author, understands why his countrymen turn against shopkeepers who profit from — but will not stay to contribute to the wealth of — this post-apartheid nation. Asad's single-minded, risk-taking, almost superhuman dedication to his work in the midst of an angry people who want to kill him makes for a breathtaking narrative. Yet Steinberg details the consequences of Asad's ignorance of history, a factor that helps to explain why he became a target — and why his first wife leaves him when she realizes that he may well be killed and his family destroyed.

Asad's gripping story is enhanced by another tale, of the conflicted relationship between biographer and subject. Steinberg often presses a reluctant Asad to tell his full story, and at the beginning Steinberg succeeds in almost Proustian fashion. When Asad says he cannot remember much of his native Mogadishu, Steinberg says, "It doesn't matter … just tell me what comes into your head." Asad then snaps a twig in two, and the smell of it reminds him of making ink as a young boy, when he pinched the branch of an agreeg tree to render its sap, which is then mixed with charcoal and water so he can write out the verses of the Qur'an at his madrassa.

Only through Steinberg's adroit persistence — he knows when to probe and pry and when to retreat when Asad seems nettled by constant questioning — can the account of Asad's remarkable, almost miraculous life journey emerge, a quest that eventually takes him to Kansas City, Mo. In the end, Asad loses interest in Steinberg's book — not because of any dispute about the story itself, but because of Asad's desire to move ahead rather than recount his losses. And that is always the way: The biographer's yield is nearly always something different from his subject's aspirations.

Carl Rollyson is the author of "Essays in Biography" and "Biography: A User's Guide."