""That Kennedy Girl"" tells the story of Kathleen Kennedy and her struggle to live her own life her own way, in spite of enormous pressures from her parents and the rest of the clan. Only her brother Jack, whom she loved profoundly, seemed to understand her. It was, perhaps, the saddest of all the Kennedy tragedies. Kathleen lost both her husband and her brother, Joe, in World War II, and shortly thereafter, at the age of 28, died herself in an airplane crash.