WHEN ANNE HANSON'S DAD FIRST ASKED her to investigate the secret past of his parents, little did she know what she was getting into. For two decades, despite all her digging, she failed to unearth even the tiniest speck of evidence that the families of her grandparents, Frank and Ida Hanson, had ever existed. If her quest were a detective novel, its title would have been, "The Case of the Missing Ancestors." Finally, Anne unearthed her grandparents'...