A woman whose twin brother had disappeared years ago and was believed to be dead, is found dead herself with a gunshot wound to the abdomen. Evidence and autopsy both suggest that she took her own life but Stella, who had been in contact with the victim for several years regarding her brother's unsolved disappearance, believes that she was close to a breakthrough in her brother's case and would not have killed herself. At Stella's insistence, the team goes back to the victim's apartment to reexamine the evidence when a man jumps out of the closet attacking Stella causing a chase to ensue on the streets of New York. Det. Flack wounds the suspect but he gets away. Stella was able to see his face and I.D's him as the victim's stepfather, who has always been was a suspect in her brother's disappearance. Evidence left behind during the chase gets Mac and the team to agree that the victim did not commit suicide. Stella works to track down the stepfather and when Stella receives a letter the victim sent to her right before her death, it shows that the victim recently regained memories of witnessing her brother's murder at the hands of her stepfather, giving the team the motive they were searching for.