The premiere of "Dexter: Original Sin" opens with a dramatic scene where Dexter is hastily conveyed to the hospital, clinging to life after a near-fatal gunshot wound. Miraculously, his heartbeat steadys, narrowly averting the grim reaper's grasp, and this pivotal moment transports us back to the genesis of Dexter's existence. In the very same emergency ward where death loomed over him, Laura welcomes her newborn son, Dexter, into the world.
Cut to Dexter Morgan, now an adult, meticulously dissecting a body in the autopsy room. His precision is nothing short of remarkable, as he expertly removes organs, earning the admiration of his supervising doctor. However, Dexter confesses a startling lack of emotion during this grisly task.
As Dexter graduates from high school, the subtle hints of his psychopathic tendencies surface, yet it remains a Dexter narrative incomplete without the presence of the macabre. It isn't long before the specter of death rears its ugly head once again. Sergeant Morgan and Captain Spencer are summoned to a crime scene, where two lifeless bodies lie sprawled on the ground. While evidence, such as a TV remote, is dusted for fingerprints, Dexter sits nonchalantly at dinner with his family, oblivious to the turmoil brewing outside. His sister, Deb, exudes a rebellious spirit, while their father, Harry, orchestrates a strategy to steer Dexter onto a straighter path. He orchestrates Deb's plan to bring Dexter along to an upcoming lavish party, all while being acutely aware of Dexter's dark urges. Harry reassures Dexter that their meticulously crafted plan, centered around a medical residency, will quell his dark impulses.
At the campus, Dexter's fascination is piqued by the Miami Metro Forensics booth, where Masuka's attempts to charm women border on the comical. A surprising revelation unfolds – Harry is embedded within the department, and Dexter, with his innate aptitude for crime scenes, swiftly deduces that two photographs hint at the same perpetrator.
The police department is under siege, grappling with three separate home invasions that left eight individuals deceased. Fingerprints lifted from the remote lead them to Levi Reed, a prime suspect. The authorities swiftly act, raiding his premises and securing his arrest.
Regarding Dexter, he arrives at the party accompanied by his sister, Deb, and they promptly separate to enjoy the festivities individually. Dexter finds himself being kissed by a girl, but the affection is far from mutual; he remains unmoved. Meanwhile, Deb indulges excessively in alcohol and finds herself in an upstairs room with a boy who attempts to exploit her vulnerability. When Dexter discovers this situation, his rage takes over, leading him to assault the boy and reaching for a knife in a fit of fury—until Deb intervenes and halts his actions. Subsequently, the duo is ejected from the party and arrives home late, where they find Harry anxiously awaiting their return. His insomnia is a direct result of an enduring nightmare from a traumatic past incident.
In the present day, Harry ventures out with Dexter for another hunting expedition but confesses during their journey that the outings are no longer effective. Dexter acknowledges his struggle to curb his impulses, even revealing that he narrowly escaped committing murder. However, the mood takes a drastic downturn when Harry suddenly collapses, apparently suffering a heart attack. Dexter rushes him to the hospital, where he and Deb sit anxiously in the waiting room. Harry's health scare is partially attributed to stress, much of which stems from Dexter's behavior, a realization that dawns on the siblings.
Harry remains hospitalized for a week, yet his condition fails to improve. During this time, Dexter becomes suspicious of a nurse named Mary, particularly when she meticulously clips the obituary section from the newspaper. This action sets off alarm signals in Dexter's mind, and he starts to suspect that she might be the culprit hindering Harry's recovery.
With a folder serving as a macabre symbol of her defeated victims, Dexter uncovers a startling revelation: the injections administered to Harry contain an abnormally high concentration of potassium nitrate. Harry grants Dexter the green light to eliminate Nurse Joy, prompting a sly grin to spread across his face. Dexter, who has anticipated this moment for his entire life, finally sees his chance to play the game.
The fear emanating from Nurse Joy titillates Dexter, ultimately leading him to commit her murder and dispose of her remains. He drives her to a remote lake known as Alligator Alley, where he allows the ferocious reptiles to consume her body entirely. He pockets her earrings as a grim trophy, unaware that this act will soon backfire.
Upon returning home, Dexter discovers the police awaiting him outside, kindly intending to deliver some groceries while Harry recovers. This is also the occasion where we meet Tanya Martin, the head of the Forensics department, who happens to offer Dexter a paid internship. He reluctantly agrees to consider the offer.
As Dexter graduates and Harry returns home, a poignant conversation unfolds between father and son about the murder. Dexter recounts the details with a hint of satisfaction, admitting that the act of killing brought him a strange sense of fulfillment. When Dexter leaves, Harry finds it difficult to suppress his tears.
Nonetheless, Dexter eventually reports for his internship, marking the beginning of a new chapter in his life, filled with both promise and peril.
