Dexter's world is rocked when a rival serial murderer, dubbed the Ice Truck Killer by the media, privately contacts him and reveals that he knows Dexter's grisly secret. Meanwhile, Dexter's sister Debra is transferred to Homicide.

Dexter and Debra try to dissuade their boss from pursuing a security guard they believe has been wrongly identified as the Ice Truck Killer. Dexter's girlfriend receives an unwelcome visit from an associate of her imprisoned husband.

The Ice Truck Killer begins leaving body parts from his victims at sites that relate to memories from Dexter's childhood, forcing him to confront his dark personal history.

The Homicide Division is buzzing after the Ice Truck Killer's latest victim is found mutilated but alive, while Dexter gets in over his head when he stalks a murderous human trafficker.

The Ice Truck Killer leaves Dexter a surprise at the scene of one of Dexter's recent kills, placing him firmly in the cross hairs of his own Homicide Division colleagues.

The Ice Truck Killer is finally identified, but something about the suspect doesn't sit right with Dexter, who must also deal with the menacing return of Rita's paroled ex-husband.

The strange suicide of a powerful woman leads Dexter to suspect her shrink of murder, but he gets a shock when a visit to the suspect opens up dark secrets from Dexter's past.

Dexter is joined by Rita, Debra and Rudy for a weekend away when he learns that his biological father, whom he was told died thirty years ago, has just recently passed away and left him everything he owned, including his house.

The Ice Truck Killer leaves Dexter the most horrifying crime scene imaginable, forcing him to confront a horrific suppressed memory from his past; Rita must hire a lawyer when her ex sues for sole custody of their children.

The Ice Truck Killer takes extreme measures, forcing Dexter into a trap that will forever change his life, while Doakes begins to harbor suspicions about Dexter's odd behavior.

In the Season One finale, Dexter follows the clues left for him by the Ice Truck Killer, while Paul tries to convince Rita that Dexter is dangerous.