Dexter’s loyalties are put to the test as he follows clues that the Ice Truck Killer leaves for him. But as Dexter goes on the hunt, he wonders just how deep he will have to go down the Ice Truck Killer’s dark and demented path. Doakes, still thinking that Dexter may be the Ice Truck Killer, uses questionable methods to stop Dexter from his hunt for the Ice Truck Killer. Meanwhile, as Dexter remains unavailable to Rita, her ex-husband, Paul, tries to convince her that Dexter is a very dangerous man to have around their children.
The Ice Truck Killer strikes again, leaving a real nightmare before Christmas at Santa’s Cottage. But this time, Dexter notices that the kill is not as ‘tidy’ as the previous kills, as if the Ice Truck Killer is rushing to leave Miami. But in reality, the Ice Truck Killer has kidnapped someone very close to Dexter to lure him into a trap that will change Dexter’s life forever. Meanwhile, Sgt. Doakes notices that Dexter has been acting strangely around the Homicide division, making him wonder if in fact, Dexter is the Ice Truck Killer.
Dexter’s world is shaken when he is called to the crime scene of a massacre unlike any that he’s ever seen before… or so he thinks, until a series of memories comes streaming back that shock him to his core. Meanwhile, Rita has to hire a lawyer when Paul brings a surprising case against her to take sole custody of their children. Batista follows a new lead on the Ice Truck Killer case that brings him one step closer to apprehending the sadistic serial killer. But does it bring him too close?
Dexter receives a registered letter that informs him that his biological father has recently died. This comes as a shock, because Harry, Dexter’s adoptive father, had told Dexter that his real father had died over 30 years ago. As Dexter takes off to reconnect to his shadowy past, Rita decides to come along to help him make it through the weekend. Then Debra and Rudy join them for the weekend at the dead bio-dad’s house and things become even more awkward. Back in Miami, Doakes is involved in the questionable shooting of a middle-aged Haitian man. Internal Affairs investigates and Batista has to decide if he’s going to tell the truth about the shooting, or back Doakes’ untrue version of the actual incident.
While looking into a series of suicides of high profile, powerful women, Dexter realizes a pattern: they all saw the same shrink. Dexter goes into stalk mode and becomes a patient of the shrink to ascertain whether or not he is the killer that he seems to be. Unexpectedly, the shrink helps Dexter unlock dark secrets from his past. Debra’s latest relationship with Rudy also quickly heats up. Dexter’s relationship with Rita, however, seems to be in danger as Paul works his way deeper into Rita’s life and much to Rita’s consternation, the kids love him and he’s actually civil to her. Meanwhile, Dexter’s certainty that Neil Perry is not the Ice Truck Killer helps LaGuerta to decide to not just accept Neil’s confession, despite mounting evidence to the contrary.
