Josh Mankiewicz talks with Andrea Canning about her latest Dateline episode, “A Promise to Gloria.” In 1984,  Yvonne Pointer vowed to track down the killer of her 14-year-old daughter,  Gloria, who was murdered on her morning walk to school. Andrea tells Josh why Yvonne’s 30-year search for truth has made such an impression on her and what Yvonne is doing now to protect other young people from harm.