Scully and her mother travel to Bill Jr.'s house--located at a U.S. naval station in San Diego--several days before the Christmas holiday. There they are greeted by Bill Jr. and his pregnant wife, Tara, who is expected their first child. Not long after her arrival, Scully answers the telephone. On the other end of the line is a woman who sounds exactly like Scully's deceased sister, Melissa. The voice tells Scully, "she needs your help." Unnerved, Scully has the FBI trace the call which, it turns out, was made from the Sim residence. Scully discovers the home is the scene of a criminal investigation. Detective Kresge allows her access to the bathroom, where a dead blonde woman, Mrs. Robert Sim, reclines in a tub full of bloody water, the apparent victim of a suicide. Later, Scully observes the victim's husband, Marshall, and three-year-old Emily Sim. Scully stares at the girl, intrigued by her face. Detective Kresge tells Scully that phone records do indeed indicate that an incoming call was made from the Sim residence to Bill Jr.'s house. But at the same time, there is no record of an outgoing call. Records also indicate the phone had been off the hook for three hours.

     Scully tells her mother she's very happy for Bill and Tara... then admits that, as a result of her abduction, she cannot conceive a child of her own. Later that night, Scully experiences a dream in which a young Bill Jr. kills her pet rabbit. During the same dream, she encounters little Emily Sim. Scully is awoken by another call from the mysterious woman. The voice tells Scully to "go to her." The call is again traced to the Sim residence, where Marshall assures Scully that no one used the telephone. From Scully's viewpoint at the front door, she observes two dark-suited men sitting at the kitchen table. The next day, Scully requests--and is given access to--all evidence in the Roberta Sim case. She also phones the FBI and requests the case file on her sister, Melissa. Noting several discrepancies in the file, Scully performs an autopsy on Roberta's body. She discovers a complete absence of medicine tablets inside her stomach. She does, however, notice a puncture wound on the heal of her foot. A search of the Sim house turns up a hypodermic needle in the trash. Marshall claims Emily suffers from anemia and requires daily injections.

     Scully tells her mother that a PCR test, which has a sixty-percent accuracy rate, suggests that Emily and Melissa's DNA match (a more comprehensive test will be available in several days). This, and the undeniable physical resemblance between the pair, leads Scully to conclude that Emily is Melissa's daughter. She reminds her mother about a period in 1994 when Melissa's whereabout were unknown... and speculates that she could have given Emily up for adoption. Later, Scully experiences another dream, during which Mrs. Scully gives her the crucifix she wears around her neck. When Scully awakens, Detective Kresge informs her about large bank deposits made by Marshall over the previous eighteen months. The money came from a pharmaceutical company called Prangen Industries. Scully and Kresge interview Dr. Ernest Calderon, who works for the company. He explains that Emily was participating in a clinical trial. When Roberta tried to pull her daughter from the program, the company agreed to send her money as a gesture of good will. Calderon also reveals he prescribed Marshall sumatriptan injections after he complained of migraines. Later, Marshall is arrested for his wife's murder. As a result, Emily is placed in the care of Social Services. Before Emily is driven away, Scully places her gold cross around the girl's neck.

     Marshall Sim confesses to the murder. But Scully finds it odd that witnesses had provided him an alibi. She and Kresge drive to the jail, where they find his body hanging from a makeshift noose. Later, Scully tells her brother that the death was made to look like a suicide. Susan Chambliss, a social worker, tells Scully that her application to adopt Emily was rejected. Scully states that the time has come for her to place her personal life ahead of her career. Cambliss promises a review of Scully's final application. On Christmas morning, Scully receives a delivery from an FBI courier. The final DNA test results reveal that Scully is Emily's mother.