Mulder experiences a series of dreams which lead him to finding a skeleton buried beneath the earth of a murdered child.
He soon realizes after investigating that the child was in fact murdered by a serial killer that Mulder helped to put away, John Lee Roche. Roche killed 8-10 year old girls, strangling them and cutting a heart shaped piece of fabric from their clothes and when he was captured he confessed to 13 murders.

Mulder soon concludes that because of this discovery, Roche must have killed more children than he confessed to and when Mulder has another vivid dream detailing where he hid the paper hearts that Roche cut from his victims, he locates them and finds a total of 16 hearts which means there must be two more unfounded victims.

Mulder and Scully go to interview Roche in jail but he turns out to be very uncooperative about the murders that he committed. He does comment oddly to Mulder that he is taking the case personally which he does not understand but comes clear in Mulder's next dream in which he goes back in time to the night of his sister, Samantha's abduction. He sees the door burst open but instead of it being a gray, it's Roche who abducts her.

This means that Roche could indeed have abducted Samantha so he goes back to interview him and Roche claims that he sold a vacuum to Mulder's father before Samantha's abduction. The remarks he makes do indeed say that he did abduct Samantha but when Roche becomes uncooperative again, Mulder loses control and hits him. Scully is worried about Mulder's recent actions and tells him that the images he sees are not real but his subconscious. Mulder is not satisfied and does not know what to believe so he is convinced in finding out the truth about Samantha's disappearance. He searches the basement of his family home and to his horror he discovers that the vacuum he finds is the same make and model that Roche claimed he sold to them.

When Skinner finds out that Mulder hit Roche in prison he denies him further contact with the prisoner. Mulder confides in Skinner about his fear of his sister's abduction which convinces Skinner to allow Mulder to see him again as long as he is accompanied by Scully.

Mulder goes back to visit Roche where he gives him what Roche had been looking for, the paper hearts of his victims. Mulder now demands that Roche describe what happened on the night of Samantha's abduction and the description exactly matches the vision that Mulder remembers. Roche is not willing to tell Mulder whether one of the hearts belongs to Samantha so instead allows Mulder to pick a heart at random, the heart he picks will allow Roche to tell Mulder where the body of that victim is. Mulder locates the victim but it is not Samantha's body.

Mulder and Scully go back to interview Roche where, sensing that Mulder is desperate, says that Mulder must release Roche and take him to where Samantha was abducted where he will reveal what really happened to her. Scully becomes annoyed with Mulder and drags him away but, unaware to Scully and Skinner, Mulder sneaks back to Roche's cell and takes him to his home in Martha's Vineyard. Except, Mulder takes him to the wrong house where Roche admits all about Samantha's abduction. Mulder now realizes that Roche is tricking him and concludes that while profiling Roche, Mulder and him must have developed a connection which allowed Roche to get into his mind and find out the details about Samantha.

Mulder plans to return Roche to his cell in the morning but after another vivid dream about Samantha, he wakes up in his own handcuffs with his ID gone. Using Mulder's badge, Roche kidnaps another girl, Caitlin while Mulder takes the blame for releasing Roche and he admits that Scully was right all along.

Mulder locates Roche and shoots him just in time to save Caitlin's life. But now that Roche is dead, will Mulder REALLY know what happened to his sister.....?