I sat down with Riley Keough, Elvis’s first-born grandchild, for her first in-dept interview since her mother, Lisa Marie Presley, passed away unexpectedly last year. Before her death, Lisa recorded hours of stories from her life for her memoir “From Here to the Great Unknown.” These tapes had hours of stories about her father Elvis Presley, her famous family, motherhood, deep addiction, and ever-present grief. “An Oprah Special: The Presleys—Elvis, Lisa Marie, and Riley” will air this Tuesday,