For the past decade, Dexter has assimilated into small-town life as a beloved member of the Iron Lake community; when a local hotshot begins behaving recklessly, he questions whether he can continue to suppress the murderous urgings.
Dexter's cabin becomes home base when a missing person case turns into a crime scene; Dexter is trying to reunite with his son, Harrison.
The investigation that Dexter has caused is making it difficult for him to make things right with Harrison, who has made a name for himself at school as a member of the wrestling team.
The father of the person whom Dexter killed makes an unexpected announcement; Harrison is considered a hero to the entire town after he was involved in a serious incident at school.
Dexter's method of protecting his son from drugs unleashes his Dark Passenger; Angela and Molly's New York City trip leaves them wondering about a well-respected member of the community.
Someone has discovered Jim Lindsay's secret identity, leading Dexter to realize that he might not be the only serial killer in town; Harrison spirals out of control during a wrestling match; Angela makes a dark discovery of her own.
Dexter turns from predator to protector out of concern that a serial killer has set its sights on someone he cares deeply about; Angela arrests someone who may be the culprit of a cold case; Harrison turns to a dangerous person as a father figure.
Dexter fights for his life in the woods, leading to a confrontation in an abandoned summer camp; Harrison finds himself torn between two father figures who can lead him down two very different paths; Angela makes some disturbing discoveries.
Dexter and Harrison find themselves closer than ever over Christmas break, bringing father and son into the crosshairs of a serial killer; Angela starts to wonder if Iron Lake is not the safe place she always thought it was.