After witnessing her brother kill, Debra attempts to reconcile with Dexter while struggling to cover up their involvement with the murder.

Miami Metro sets out to unearth new evidence on a claim from a local convict that he has new information regarding a 15-year-old crime spree; Debra tries to cure Dexter of his killer tendencies.

Dexter tries to bring Debra on board with his new target. While the Ukrainian mob seeks revenge for the killing of one of their own, Quinn grows close to a dancer at their strip club.

After capturing a deadly killer, things go awry for Miami Metro, sending Debra into a tailspin. In an effort to help his sister, Dexter enters into a dangerous game of cat and mouse, while the Ukrainian mob continues to seek revenge.

While trying to uncover why someone was killed on his boat, Dexter must out-maneuver a vengeful Isaak. New leads are brought to light on the Wayne Randall case by Hannah McKay, Randall's alluring former accomplice who Dexter discovers has a secret.

Quinn falls back into his old ways as he makes some questionable choices to protect Nadia. Things heat up as Dexter and Hannah grow closer, but when Sal Price discovers the two are involved, he wants the exclusive story.

Fresh out of jail, Isaak renews his pursuit of Dexter while Quinn continues his power struggle with the Koshkas. Dexter tries to keep Debra in the dark about his relationship with Hannah, but a surprise visit from Astor, Cody and Harrison throws a wrench into his plans.

As Dexter scrambles to track down Isaak, a power struggle erupts among the Koshka Brotherhood, which could prove to Dexter's advantage. Meanwhile, Miami Dade tries to smoke out the Phantom Arsonist.

Dexter is unnerved when Hannah's father pays him a surprise visit; the Phantom Arsonist's crimes become more vicious; and Quinn defends Nadia's honor and finds himself in a volatile situation. Meanwhile; LaGuerta asks a former superior for help on the Bay Harbor Butcher case.

Dexter must protect himself when LaGuerta closes in on his secret.

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.

Miami Metro continues their hunt for the Brain Surgeon, while Dr. Vogel enlists Dexter to do her bidding based on her own personal experience with her previous patients. Debra continues to track down her PI case and has to take matters into her own hands.

Dexter continues his manhunt for the Brain Surgeon. Dr. Vogel tries to prove to Dexter that he’s perfect as a psychopath. Debra’s PTSD kicks in and she makes a desperate plea to confess to LaGuerta’s murder.

Dexter tracks down another potential serial killer from Dr. Vogel’s list. Quinn celebrates his passing of the Sergeant’s exam by defending Debra’s honor in a fight. Dr. Vogel begins treating Debra for her PTSD.

Dr. Vogel gets abducted by the Brain Surgeon, while Dexter and Debra try and rescue her. Masuka finds out he has a daughter.

Dexter monitors a young psychopath to see if he is suited for his table. Dexter and Debra finally get back to normal, but are surprised by his ex, Hannah.

Dexter enlists Dr. Vogel's help to lure the Brain Surgeon to a location in order to get him on the table. Later, an important person in Dexter's life is murdered before his eyes.

Dexter is torn between fleeing the country with Hannah and Harrison, and taking Saxon out once and for all.