Dexter continues to juggle fatherhood with the life of a serial killer, while Miami police investigate the mysterious murder of a guy who had parts of his brain removed.
The Miami police continue to pursue the Brain Surgeon, and Dexter is enlisted to help Dr. Evelyn Vogel, while Debra finds herself forced to take drastic measures during an investigation.
Dexter continues to look for the Brain Surgeon, while Dr. Evelyn implies that Dexter is not an ideal psychopath. Debra suffers from post-traumatic stress disorder and tries to seek help in vain.
Dr. Evelyn takes on the task of treating Debra for PTSD, while Dexter looks for another likely serial killer from her list, and Quinn passes the sergeant test.
Dr. Evelyn Vogel meets with the surgeon who removed parts of his victim's brain, while Dexter and Debra try to protect her, and Masuka discovers that he has a daughter that he knows nothing about.
Dexter watches a young man with mental illness to see if he meets the criteria for a serial killer. He and Debra return to normal, but the reappearance of someone from Dexter's past turns things around.
Dexter pursues Hannah to get answers as to why she returned to Miami before he mentors a protege and begins teaching him his own rules.
Dexter decides to go after Zach, fearing that he may have killed someone innocent. At the same time, Dexter tries to help Hannah flee the country, and faces more complex challenges.
Dexter investigates a mysterious murder that affects him personally, and Dr. Vogel is in for a huge surprise when someone she knew in the past reappears in her life.
Dexter attempts to lure the Brain Surgeon into an elaborate trap and catch him with the help of Dr. Vogel, but he witnesses a new murder that turns the course of events and changes his plans.
Dexter becomes torn between escaping with Hannah and Harrison or eliminating Saxon, but his inaction ultimately leads to horrific and surprising results.
Dexter faces deadly challenges after the announcement that a hurricane is approaching and threatening to destroy the coastal city of Miami. Many questions are raised about his position and the future of those around him.