Thirty-eight days after killing his only brother, the infamous Ice Truck Killer, Dexter Morgan (MICHAEL C. HALL) still has problems. Sgt. Doakes (ERIK KING) remains convinced that Dexter has something sinister to hide.

His sister Debra (JENNIFER CARPENTER) has moved into his apartment, unable to get over the pain of nearly being murdered by her fiancé Rudy, the Ice Truck Killer. And his girlfriend Rita (JULIE BENZ) suspects Dexter of framing her ex-husband Paul and sending him to jail.

As a result, Dexter hasn’t been able to do what he does best – keep Miami clean by taking out its coldblooded killers. Eager to get back in the serial-killing saddle, Dexter manages to elude Sgt. Doakes, but even then, Dexter finds that killing these days isn’t easy.

Dexter’s difficulties multiply when evidence of his murderous activities surfaces in Miami. Soon, the city has a new serial killer to focus on, one far more prolific than the Ice Truck Killer. Frank Lundy (KEITH CARRADINE), an FBI agent famous for catching serial killers, flies in from Washington to head up the search for Dexter. Lundy forms a taskforce, which includes Batista (DAVID ZAYAS), Masuka (C.S. LEE) and Debra, whose sole purpose is to uncover the identity of the newly dubbed “Bay Harbor Butcher.”

After losing her leadership of the homicide division, Lt. Laguerta (LAUREN VÉLEZ) has to readjust to life as a field detective in the bullpen, but she has long-range plans to regain her leadership and get her office back. She begins to buy into Doakes’ suspicion of Dexter and becomes concerned for Doakes and his obsessive nature. Laguerta will have to make some hard decisions regarding Doakes’ fitness as a detective that will severely test their friendship.

Rita, meanwhile, mistakes Dexter’s suspicious behavior for drug addiction and pushes him into a recovery program, where he meets a mysterious woman with a dark past named Lila (JAIME MURRAY). If Rita is the perfect woman, Lila just might be the perfect woman for Dexter. As the two of them bond over their inner demons, Dexter’s tortured history comes back to haunt him. Details of Harry Morgan’s (JAMES REMAR) life come more into focus for Dexter and he realizes his iconic image of his foster father and “Harry’s Code” are more complex than he once thought.

Dexter can’t pause for a breath as the noose tightens. Will he be able to continue his serial-killing ways, while keeping tabs on Lundy and the task force? Or will Doakes finally uncover Dexter’s dark past?