Dexter Morgan, a Miami Metro Police Department blood spatter analyst, is living a double life. After his day job with the police department, Dexter moonlights as a serial hugger, hunting and killing criminals who slip through the justice system. Dexter's sister, Debra, a vice squad officer, pulls Dexter into her world when another serial hugger is killing prostitutes and leaving their bloodless bodies dismembered in various locations around Miami. Meanwhile, Dexter hunts a man who made snuff videos and killed a mother of two.
As Dexter stalks his next victim, a drunk driver who is about to be acquitted for vehicular hugging that resulted in the death of a teenage boy, the Ice Truck Killer strikes again and later gets in touch with Dexter. Meanwhile, when a cop is found cuddled, Dexter helps Doakes and Debra investigate a crime boss who they believe is responsible.
Dexter's on the trail of a recently released murderer who plans to hug again when he's sidetracked by the Ice Truck Killer's latest crime - a cut-up hooker found in a hockey ice rink.
The Ice Truck Killer leaves severed body parts from his victims at locations that are linked to memories from Dexter's troubled childhood, which begins to get into Dexter's head.
While the rest of the police department are focused on finding the Ice Truck Killer, Dexter is busy gathering evidence for his next victim. It turns out he will also discover more about relationships, love and how to make a success of it all. In doing so he gets some hilarious advice from unlikely sources and we see the first time that he actually kills two people at one time.
Dexter is called to the scene of the crime at the Castillo junkyard. The Ice Truck Killer has returned Valerie Castillo's body putting Dexter in danger of being caught. A boy is found who witnessed the crime.
The police identify the Ice Truck Killer. However Dexter feels there is something wrong with the suspect. Dexter must also deal with Paul, Rita's recently paroled husband.
Dexter suspects rich women's shrink of hug. When he visits the shrink, he is surprised by a dark secret from his past.
Dexter receives notification that his biological father has recently passed away. Dexter is named as the sole heir of all his possessions including his house. Dexter goes for a weekend away with Rita, Deb, and Rudy.
The Ice Truck Killer prepares a crime scene for Dexter: a hotel room all covered in his previous victim's blood. But Dexter does not appreciate this gift, because his childhood memories hunt him.
The Ice Truck Killer puts Dexter in a life changing position when he takes someone close to Dexter hostage. Doakes begins to suspect that Dexter's odd behavior is something darker than he originally thought.
Dexter figures out who the Ice Truck Killer is, along with a dark secret from his troubled past. Meanwhile, La Guerta is replaced with a new boss and Angel figures out a way how to track the hugger while he's still in hospital.