Detectives Briscoe and Logan investigate the murder of a psychiatrist, Dr. Lillian Hampton who is found bludgeoned to death in her office. Her last appointment of the day was with a young woman, Megan Nelson, but the Director of the clinic heard a man's voice in her office some time after that. After eliminating other suspects, they come to believe that the man in the office was Megan's father Frank Nelson. Megan had been seeing Dr. Hampton for some time and was diagnosed with multiple personality disorder. ADA McCoy decides to prosecute Mr. Nelson when Megan reveals an old memory of him killing her mother. When evidence suggests otherwise, they have to consider if one of Megan's other personalities may be responsible.