"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 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.