Goren and Eames investigate the death of a wealthy publisher killed by a car bomb.
During the investigation, Goren and Eames discover that the victim was murdered after he demanded to meet a disabled girl he had been supporting. She is known as an orphaned and elusive teenage author whose personal tragedies have spawned best-selling books and profitable charities.
Shortly after, the detectives interview one of her editors, but they begin to suspect the girl in question does not even exist; no one can say they have ever met her. They think that her foster parents are running an elaborate fraud. People around her become polarised into "believers" and "non-believers", hence the episode's title.
As the detectives close in, they follow their instincts to extract a confession from the potential killer. A slight twist is introduced towards the end, only to find that everyone involved in the case has been living a lie.