The Scholastic edition does not suggest that this is book three of a series. Sarah lives in the Kalahari semi-desert with her zoologist-researcher father. Her mother died several months before. A motley group of teens are coming to stay for two week, possibly the beginning of a new source of funding for the research station. Things go badly. "Poachers", a horrific "disease", and a silver lion. Lots of action, I will give it that.