"The Ice Truck Killer" strikes again and new homicide officer Debra is assigned the case, but she gets reprimanded for violating the chain of command; flashbacks offer insight into Dexter's homicidal tendencies and take him back to his first time "taking out the garbage"; Doakes gets on the bad side of a drug kingpin.

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.

The homicide division is handed an unbelievable lead when the Ice Truck Killer's latest victim is found alive but mutilated; Dexter is on the trail of a person who traffics in humans.

The squad identifies the Ice Truck Killer; Rita's ex-husband, an abusive addict, is paroled.