Brennan and Booth are called to the scene of a deadly fire at a D.C. prison to investigate what they believe is the death of Brennan's incarcerated adversary, serial killer Howard Epps, whose body was found burned beyond recognition. But Brennan's examination leads to the chilling realization that the charred body is not Epps', but that of a D.C. fireman Epps killed in order to fake his own death and escape from a maximum security prison amid the commotion of the fire. After paying a visit to Epps' former wife, Caroline, to determine if she has any clue as to his whereabouts, Brennan and Booth leave empty-handed, but are concerned for Caroline's safety with her ex-husband on the loose. Their fears are quickly realized as they get concrete proof that Epps has killed again. As Epps leads Brennan and Booth into a game of cat and mouse, it's clear he is targeting them and the people they're close to, all the while giving them clues they desperately try to decipher before Epps takes another victim. While Cam conducts an autopsy on Epps' latest victim, Booth implores her to break protocol to save time and jump to a later step in the process. Against her better judgment she does, but she is sprayed with a deadly poison and critically injured. As Cam's life hangs in the balance, Booth, Brennan and the rest of the Jeffersonian team race to figure out what deadly substance is killing Cam and determine Epps' whereabouts before Cam becomes his latest victim.