The Ice Truck Killer sets a trap for Dexter by kidnapping someone close to him; Dexter's increasingly odd behavior piques Doakes's interest.

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.

Dexter is attacked by the man who murdered his mother. Meanwhile, Lila wants to get closer to Dex, and Debra and Lundy close in on the Bay Harbor Butcher.

Dexter has put his life back together but things may fall apart soon. His new victim is also being targeted by Assistant District Attorney Miguel Prado. Deb has to decide how to handle Internal Affairs, as they want her to turn on her new partner.

Ramon's career may be in jeopardy due to his obsession with Oscar's killer. Meanwhile, Dexter does a great job in keeping Ramon off balance by manipulation. Deb refuses to "be a rat" after Internal Affairs presses her to come up with more dirt on Quinn. Also, Rita and Dexter decide it's time to tell the children about her "condition," and Angel's quest for companionship nearly get's him in deep water.

It is the day before Dexter's wedding and Dexter must deal with two people targeting him, while preparing for his special occasion. Meanwhile, Angel tells Deb he's put her in for a promotion, but after he finds out some information her shield may be gone before she gets it.

Recent events spur Dexter into his own investigation of the Trinity killer. His motivations are now personal, and the clock is ticking. But the closer Dexter gets, the more he realizes that Trinity is unlike any monster he’s previously encountered. Meanwhile, Debra blames herself for events that were out of her control, and in so doing pushes away those closest to her. As LaGuerta and Batista close in on the Vacation Murderers, Batista realizes he can use Quinn’s relationship with a certain reporter to his advantage. And when Rita discovers a secret Dexter’s been keeping from her, she begins to realize just how little she knows about the man she married.

Dexter finally believes he understands the beast known as Trinity. But when a ten-year old boy goes missing, Dexter is forced to question everything he’s learned up to this point.

Homicide uncovers some key evidence linked to one of Dexter's and Lumen's prior victims; Debra identifies two more suspects in the case.

It’s been 6 months since LaGuerta’s murder – and Dexter is still managing life as a dad, brother, and serial killer. Debra now works as a PI for a private firm and Batista has replaced her as Lieutenant. Meanwhile, Miami Metro investigates the murder of a man who has had pieces of his brain removed.