Based on The New York Times best-seller, The Secret Life of Marilyn Monroe begins with the young Norma Jeane Mortenson as she battles a lonely, loveless existence with an absent and mentally ill mother. She ultimately reinvents herself as the sex symbol of an era. A fragile artist, she is very different from the larger-than-life image she portrayed. The great secret of Marilyn's life is that her mother, Gladys (Sarandon), remained a vital - and troubling - part of her world. Her marriages to Joe DiMaggio (Morgan) and Arthur Miller collapse in part due to her own inner demons and the onslaught of her mother's illness. As Marilyn cares for her mother, her obsession with President John F. Kennedy leads to a breakdown and hospitalization. Still, she gives the performance of her life as Marilyn Monroe.