Dexter Morgan, a blood spatter analyst for the Miami Metro Police Department, leads a double life as a vigilante serial killer. The series opens with Dexter narrating his life, explaining his childhood trauma of witnessing his mother's murder, which shaped his dark urges. He was adopted by Harry Morgan, a police officer who recognized Dexter's tendencies and taught him a code to channel his urges towards killing only those who deserve it.

In the first episode, Dexter is introduced at work, where he interacts with his colleagues, including his sister, Detective Deborah Morgan, who is eager to prove herself in the department. Dexter's dark side is hinted at when he prepares to kill a man named Mike Donovan, who is a child molester. Dexter follows his code, ensuring that he only targets those who have escaped justice. He successfully kills Donovan, disposing of the body in a meticulous manner.

As the investigation into a series of gruesome murders in Miami unfolds, Dexter becomes intrigued by the case of the "Ice Truck Killer," who is leaving bodies drained of blood and arranged in a disturbing manner. The killer's methods resonate with Dexter, and he begins to feel a connection to the murderer. Meanwhile, Dexter's personal life is complicated by his relationship with Rita, a woman with two children who is trying to escape her abusive ex-husband.

Throughout the season, Dexter continues to balance his life as a forensic analyst and his secret life as a killer. He attends a support group with Rita, where he struggles with his emotions and the facade he maintains. Dexter's sister, Deb, is deeply involved in the investigation of the Ice Truck Killer, and she becomes increasingly frustrated with the lack of leads.

As the investigation progresses, Dexter discovers that the Ice Truck Killer is leaving clues specifically for him, which leads him to believe that the killer knows about his dark secret. This realization heightens the tension as Dexter tries to maintain his cover while also trying to catch the killer. He begins to investigate the killer's victims, trying to find a connection that could lead him to the murderer.

In a pivotal moment, Dexter learns that the Ice Truck Killer is actually his biological brother, Brian Moser, who was also traumatized as a child. Brian reaches out to Dexter, revealing their shared past and inviting Dexter to join him in his killing spree. This revelation forces Dexter to confront his own identity and the nature of his urges. Brian's manipulative nature becomes evident as he tries to draw Dexter into his world.

As the season progresses, Dexter's relationship with Rita deepens, but he struggles with his inability to fully connect with her and her children. He is torn between his desire for a normal life and his compulsion to kill. Meanwhile, Deb continues to investigate the Ice Truck Killer, and her determination leads her to uncover more about Brian's past.

In the season finale, Dexter finally confronts Brian, leading to a tense showdown. Brian attempts to convince Dexter to embrace his darker side, but Dexter ultimately rejects him. The confrontation escalates, and Dexter is forced to kill Brian in self-defense. This act solidifies Dexter's commitment to his code, but it also leaves him grappling with the emotional fallout of killing his own brother.

The season concludes with Dexter reflecting on his actions and the complexities of his life. He continues to navigate his relationships with Rita and Deb while maintaining his secret life as a killer, setting the stage for future conflicts and developments in his character.

At the end of "Dexter" Season 1, Dexter Morgan confronts his dark urges and the consequences of his actions. He faces off against the Ice Truck Killer, who is revealed to be his biological brother, Brian Moser. The season concludes with Dexter making a pivotal choice that impacts his relationships and his own identity.

As the final episode unfolds, the tension escalates. Dexter Morgan, a forensic blood spatter analyst for Miami Metro Police, has been tracking the Ice Truck Killer, who has been leaving a trail of gruesome murders. The killer's identity is finally revealed to be Brian Moser, Dexter's biological brother, who has been orchestrating a series of killings that resonate deeply with Dexter's own dark tendencies.

In a gripping scene, Dexter finds himself in a confrontation with Brian in a secluded location. The atmosphere is thick with tension as the two brothers engage in a conversation that reveals their shared past and the trauma that shaped them. Brian, who embodies the darker aspects of Dexter's nature, tries to persuade Dexter to embrace his violent instincts fully. The emotional weight of their familial bond hangs heavily in the air, as Dexter grapples with the implications of their connection.

As the confrontation escalates, Dexter is faced with a critical decision. He realizes that Brian's methods are not just a reflection of their shared blood but also a dangerous path that could lead to his own destruction. In a moment of clarity, Dexter chooses to reject Brian's influence. He ultimately kills Brian, a decision that signifies a turning point for Dexter. This act is not just about survival; it is a rejection of the darker path that Brian represents.

Following this intense climax, Dexter returns to his life, but the aftermath of his actions weighs heavily on him. He is left to navigate the complexities of his relationships, particularly with Rita, his girlfriend, and her children. The season closes with Dexter reflecting on his duality--his role as a vigilante who seeks justice for the victims of violent crime, while also grappling with his own dark urges.

In the final scenes, Dexter is seen in his apartment, contemplating the choices he has made. The camera lingers on his face, capturing the conflict within him. He is both relieved and burdened by the weight of his actions. The season ends with a sense of ambiguity, leaving viewers to ponder the implications of Dexter's choices and the path that lies ahead for him.

As the credits roll, the fates of the main characters are sealed: Dexter has eliminated the immediate threat posed by Brian, but the emotional and psychological ramifications of his actions linger. Rita remains unaware of Dexter's true nature, and the tension in their relationship is palpable. The season concludes with Dexter still on his journey, a complex character caught between his desire for justice and the darkness that resides within him.

In the first season of "Dexter," there are no post-credit scenes following the episodes. Each episode concludes with the standard credits, and the narrative wraps up without any additional scenes after the credits roll. The focus remains on the unfolding story of Dexter Morgan, his life as a blood spatter analyst for Miami Metro Police, and his secret life as a vigilante serial killer. The season builds tension and character development throughout its episodes, but it does not include any post-credit sequences.

Dexter Morgan is a blood spatter analyst for the Miami Metro Police Department.

Dexter's sister is Deborah Morgan, a detective with the Miami Metro Police Department, who is often involved in the investigations that Dexter secretly manipulates.

Dexter follows a 'Code' taught to him by his adoptive father, Harry Morgan, which dictates that he only kills those who are guilty of murder and have escaped justice.

The Ice Truck Killer is a serial killer who targets victims in Miami and has a personal connection to Dexter, as he is revealed to be Dexter's biological brother, Brian Moser.

Rita is Dexter's girlfriend, who is unaware of his dark secret, and she has two children from a previous marriage, which adds complexity to Dexter's life.

"Dexter," season 1, produced in 2006, is not considered family-friendly due to its mature themes and graphic content. The show revolves around Dexter Morgan, a forensic blood spatter analyst for the Miami Metro Police Department, who leads a double life as a vigilante serial killer.

Potentially objectionable or upsetting scenes and aspects include:

1. Graphic Violence: The show features scenes of murder and bloodshed, including depictions of Dexter's killings, which are often shown in detail.

2. Murder and Crime: The central theme involves serial killing, with various characters being victims of violent crimes.

3. Dark Themes: The narrative explores themes of morality, justice, and the psychological aspects of a killer, which may be unsettling.

4. Adult Language: The dialogue includes strong language and adult conversations that may not be suitable for younger audiences.

5. Sexual Content: There are scenes that involve sexual situations and adult relationships, which may be inappropriate for children.

6. Psychological Tension: The show often creates a tense atmosphere, dealing with the mind of a killer and the impact of his actions on those around him.

Overall, "Dexter" is intended for mature audiences and contains numerous elements that could be distressing for children or sensitive viewers.