S2, E10: After undergoing therapy, Helen Larson recovers a terrible memory about the death of her eight-year-old sister Marilyn. Helen tells Sergeant Ali McCormick that she and her sister were playing at a park when Marilyn wandered off. She searched for her, only to find her lying dead, her head cracked against a rock. Shocked, Helen told no one about the discovery. Two days later, Marilyn’s body was found in a shallow grave. Now, seventeen years later, Helen suddenly remembers seeing her father flee the scene.