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 killer while he's still in hospital.

Dexter is finding it hard to have closure on killing his brother. There is a new FBI agent to head the "Bay Harbor Butcher" case. Debra is finding it tough to put the past behind her.

Dexter finds out that the man who killed his mother, right in front of him, is still alive. When he tells this to Lila, she suggests he face the man, as part of his road to addiction recovery. But then as his sponsor she insists on tagging along.

Lila Tournay finds Sgt. James Doakes imprisoned in an Everglades cabin and learns from him that her object of affection, Dexter Morgan, is the serial killer known as the "Bay Harbor Butcher". She decides to help Dexter and kills Doakes by setting the cabin on fire. Meanwhile, Dexter's sister Debra questions whether her career is more important than her relationship with FBI Special Agent Frank Lundy.