What is a summary of Mother to Mother by Sindiwe Magona?

Mother to Mother, written by Sindiwe Magona, is inspired by the real-life 1993 murder of white American woman Amy Biehl, in South Africa. Biehl was in South Africa to fight against apartheid, a system of discrimination against black South Africans when she was killed by a group of young black men.
Although the real-life murder seems impossible to understand, Mother to Mother sets out to show how the murder can be shown to be understandable by following the life of a young black man named Mxolisi. Mxolisi is representative of the group of real-life killers. The story is narrated by Mxolisi's mother Mandisa and takes the form of a letter from her to Amy's mother. She is asking for Amy's mother to understand what led her son to commit such an act. The novel opens with the opening lines of Mandisa's letter:

My son killed your daughter. People look at me as though I did it. The generous ones as though I made him do it, as though I could make this child do anything. Starting from when he was less than six years old, even before he lost his first tooth or went to school. Starting, if truth be known, from before he was conceived; when he, with total lack of consideration if not downright malice, seeded himself inside my womb. But now, people look at me as if I'm the one who woke up one shushu day and said, Boyboy, run out and see whether, somewhere out there, you can find a white girl with nothing better to do than run around Guguletu, where she does not belong.

Magona uses flashbacks to tell Mandisa's story, first of all, and then that of her son. In the final pages Mandisa speaks again of the murder and how hatred and oppression have made victims of both of their children:

My son, the blind but sharpened arrow of the wrath of his race.
Your daughter, the sacrifice of hers. Blindly chosen. Flung towards her sad fate by fortune's cruelest slings.
But for the chance of a day, the difference of one sun's rise, she would be alive today. My son, perhaps not a murderer. Perhaps, not yet.

Although Mother to Mother by Sindiwe Magona is a fictional work, it was inspired by real-life events that took place in South Africa during the author’s lifetime. The novel focuses on the 1993 murder of Amy Biehl, an American student and Fulbright scholar who was instrumental in organizing democratic elections in South Africa. The story is presented as a letter from Mandisa, the mother of the man who committed the murder, to Amy’s mother, in an effort to explain the social conditions and culture that led to Amy’s murder.
The novel starts with Mandisa writing, "My son killed your daughter." She speaks honestly about the way people have blamed her for what her son did. She is "not surprised" by her son's actions but was surprised that Amy, who was white, chose to visit Guguletu, an "all-black homeland," without considering the risks. This opening chapter lays the groundwork to show the differences between each child and culture: Amy, whose experiences were grounded in believing in "goodness," and Mandisa's son, whose experiences were based on "injustice, poverty, and violence." Some of the central themes of the novel include South African apartheid, racism, and motherhood.