Season synopsis
Contains spoilers for this season and earlier seasons.
Dexter Morgan works in Miami Metro’s blood spatter unit and secretly kills murderers who escaped justice, following the code his adoptive father Harry taught him. He keeps Rita Bennett and her children, Astor and Cody, at a careful distance while presenting himself as an ordinary boyfriend. When Paul Bennett returns from prison and becomes abusive, Dexter plants drugs on him, sending him back behind bars. At work, a series of bloodless, carefully chilled bodies earns their killer the name Ice Truck Killer. Dexter reads the killer’s methods through his own habits, and his clue helps Debra move from vice to Homicide, where she begins dating prosthetics expert Rudy Cooper.
The killer turns Dexter’s investigation into a private exchange, breaking into his apartment and leaving clues that point toward Dexter’s buried childhood. When Dexter inherits a house from his biological father, Joe Driscoll, he realizes Harry concealed details of his past. Later, a gruesome, blood-filled crime scene restores the memory of his mother, Laura Moser, being murdered and dismembered in a shipping container while Dexter sat in her blood. Rudy’s closeness to Debra gives him access to Dexter; Dexter eventually identifies him as the Ice Truck Killer. Rudy is actually Brian Moser, Dexter’s older biological brother, who was also in the container but grew up apart from him.
Brian kidnaps Debra and asks Dexter to join him in killing her as a way to reclaim their family. Dexter refuses and rescues Debra, but Brian escapes; Dexter later draws him into a trap, kills him, and stages the death as a suicide. Miami Metro closes the Ice Truck Killer case without learning Dexter’s role in it. Doakes remains suspicious of Dexter, while Rita finds evidence that Dexter arranged Paul’s return to prison, leaving their relationship unsettled as the investigation ends.