In the town of Aubrey, Missouri, Detective B.J. Morrow experiences a frightening vision. In her mind's eye, she sees a man bury a corpse in a shallow grave. Certain of the exact location, B.J. rushes to a field, shovel in hand, and exhumes the body.

Using dental records, Mulder and Scully positively identify the remains. The victim is FBI Agent Sam Chaney, who disappeared in the 1940s along with his partner, Tim Ledbetter. Chaney and Ledbetter were investigating a serial murder case at the time. Mulder is puzzled by B.J. and her sudden knowledge of where the body was buried, so he and Scully travel to Aubrey hoping to uncover more about the case.

During questioning, B.J. tells the agents her car stalled near the field one night, and she noticed a dog digging in the ground. She claims it attracted her attention and, after some digging, she proceeded to find the grave. But Scully senses that B.J. is having an affair with Lieutenant Brian Tillman. She theorizes that B.J. made the initial phone call alerting police about the body from the motel where she was rendezvousing with Tillman. When confronted about the truth, B.J. admits she not only is having an affair with the married Tillman, but that she is also pregnant. She reveals how the pregnancy has triggered strange dreams in which she sees another murder.

Further research reveals that the serial murderer, dubbed the "Slash Killer" by the press at the time, would rape and murder female victims and carve the word "sister" on their chests. Mulder suspects that Chaney was a victim of the killer he was trying to catch. Using a computer, the agents analyze the victim's bone fragments hoping to find more clues. Preliminary findings suggest that letters where carved into the corpse. Those letters spelled the word "brother."

The agents are intrigued when Tillman reveals that the same serial killer who stalked Aubrey fifty years earlier has apparently embarked on another murderous rampage. Accompanied by B.J., Mulder and Scully search the scene of the latest crime. B.J. realizes the victim is the woman she saw in her dream. B.J. searches through mug shots from the 1940s and identifies the man in her dreams. He is Harry Cokely, convicted in 1945 for rape and attempted murder. He carved the word "sister" on his victim, Linda Thibodeaux, before she escaped. The agents visit Cokely, now in his seventies, sickly and house ridden.

B.J. awakens one night with blood seeping from her chest. She experiences another vision and rushes to a stranger's home, where she uncovers the body of Ledbetter.

The agents interview Linda Thibodeaux. She admits that, as a result of being raped, she gave birth to Cokely's child. She placed the baby in the hands to an adoption agency. Further investigation reveals that Cokely's son was Raymond Morrow -- B.J.'s father. The agents conclude that B.J. committed the latest series of killings. Mulder believes B.J. is working from some genetic imprint left by Cokely.

B.J. goes to Thibodeaux's home and attacks her, but she stops short of killing her. Mulder and Scully rush to Cokely's house, suspecting that B.J. will attempt revenge. Cokely dies after his oxygen equipment is sabotaged. B.J. attacks Mulder with a razor. Tillman arrives and reminds B.J. who she really is. B.J. falls into a trance and is taken into custody.