Dexter in the Dark

In the third Dexter book, "Dexter in the Dark", Dexter shows up at a crime scene where two young women have been burned and decapitate, their heads replaced with ceramic bull's heads. It's not particularly gruesome or more awful than other crime scenes he's been to, but for some reason this crime scene scares the bejeesus out of his Dark Passenger, who flees, leaving Dexter alone for the first time in his life, unsure of how to proceed, and totally uninterested in killing. His sister and the rest of the detectives are trying to solve the murders, Rita is trying to get him interested in planning their wedding, Cody and Astor are trying to convince him they're ready to kill on their own, and all Dexter can think about is getting his Dark Passenger back. Poor damaged Dexter!