Tree—short for Teresa—is a black girl with a world of problems. She has never known a father. Her mother is a nurse and stays away for weeks at a time. School means little to Tree. Not only must she cook and keep house, but she has to take care of her older brother Dab, who is marginally retarded and also exhibits symptoms of another illness; he cringes from light, grows absent-minded and distracted, sometimes experiences severe pain. Tree and her brother are extremely close; in the small apartment where they live, he has been her whole world. At the age of 14, she seems ready to expand her horizons.

Such facts are not unusual in a novel for young people, which characteristically loads its protagonist down with a host of problems as if to gather as many sympathetic readers as possible. Where these books seem contrived they...