Chimamanda Ngozi Adichie's first book, Purple Hibiscus (2004), did not follow the usual course of the African novel, the driving impetus of which remains an intense interrogation of what the Kenyan literary critic Simon Gikandi has termed "the problematic of (state) power". Instead it used the sheltered life of its narrator, the fifteen-year-old daughter of an Enugu business magnate, to account for its subdued treatment of the politics of the time. It focused on the emotional flowering of its young heroine, and on the psychological effects her father's religious fanaticism had on his wife and children. The disintegration of family the novel portrays, with its challenge to patriarchy, symbolizes the fragility engendered by political dictatorship and the anxieties and uncertainties generated by military rule.

In her second novel, Half of a Yellow Sun, Adichie squarely confronts Nigeria's political history in order to explode presumably stable notions such as nationalism, race, ethnic identity, truth, heroism and betrayal. The title is a reference to the symbol on the Biafran flag, an ironic icon that asserted Biafran's independence, while also suggesting its incompleteness and its indebtedness to some other half. Adichie's bold title signals her interest in the idea that "Nigerian identity is burdensome", as she has confirmed in an interview. She examines this burden, revisiting the theme of nationalist struggle in ways that are reminiscent of canonical African novels such as A Grain of Wheat (1964) by Ngugi wa Thiong'o. Her tone is as deceptively placid as that of Mtutuzeli Nyoka in I Speak to the Silent (2004), a disquietingly calm novel about South Africa's liberation struggle. As with Ngugi and Nyoka, Adichie's treatment of the complexities underpinning liberation avoids the shrill self-proclaimed righteousness that is heard, for example, in Ayi Kwei Armah's Two Thousand Seasons (1973) -a catalogue of Africa's myriad betrayals in slavery, colonialism and post-liberation disorder.

If Half of a Yellow Sun strikes one as a fresh examination of the ravages of war, it is because of Adichie's poignant handling of human emotions, in a range of circumstances from romance to conflict. Her focus on life in Nigeria in the 1960s settles on the way in which war turns middle-class existence on its head.

Like her countryman, Ike Oguine, the author of A Squatter's Tale (2000), Adichie has a gift for capturing the rhythms of African middle-class life: not just its political awareness but the aspirations and cultural imperatives that lend it its varied character. Thrust by the war from the comforts of the campus of the University of Nigeria, Nsukka, to the villages in the interior of Eastern Nigeria, Olanna and her lover Odenigbo encounter some very trying realities. From the naked violence and brutality of air raids and invading Nigerian soldiers to the loss of social status, economic deprivation and the domestic upheavals that come with continually shrinking spaces and opportunities, Olanna and Odenigbo are forced to embrace change. The transformation their relationship undergoes, the shifts in their own personalities and that of their houseboy, Ugwu, remind us that violence and morality are processes rather than events.

The dominant theme of return in this novel illuminates political and cultural questions alike. It underpins the portrayal of Olanna's twin sister, Kainene, and her lover Richard Churchill, a Briton who comes to Nigeria with vague ideas of writing a book on African art. Adichie's return to the story of Biafra is deliberately coloured with many artistic liberties and transgressions of strict historical truth. These represent conscious interrogations of the ownership of social memory and of the structures and sites through which national memory is carried.

Regardless of any official version of a people's history, private remembrance of the kind that fiction facilitates is key to the process of purging and bringing closure. Both Biafra and the burden of Nigerian identity must be seen for their individual and collective ability to bring about renewal. "It did not kill me, it made me knowledgeable", says Kainene, reminding Olanna of their grandfather's philosophy about hardships. Memory is ultimately about questioning the web of associations from the past, and seeking their connections and relevance to the present. For its portrayal of Nigeria's political and cultural past, Chimamanda Ngozi Adichie's Half of a Yellow Sun is a welcome addition to the corpus of African letters.

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