If you are a PD James fan, I should say up front that Innocent Blood is very different from the Adam Dalgliesh detective series. It is a psychological thriller, a slow-building mystery which starts with little steps then, as the odd details start to make sense, the tension builds. It is the story of a young woman who knows she is adopted, who exercises her right to know the names of her birth parents, and finds something she never in a million years expected.