Dexter: Original Sin season 1 episode 8 ending explained: Who killed Jimmy Powell?

Dexter: Original Sin season 1 episode 8, titled Business and Pleasure, was released on January 31, 2025, on Paramount+ with Showtime. This crime drama series continues to explore Dexter Morgan's early years and how he developed his dark instincts while following the strict code set by his adoptive father, Harry Morgan.

The episode aired at 12:00 am PT / 3:00 am ET and brought major twists to the story. One of the biggest surprises in this episode was the truth about Captain Aaron Spencer. At first, he seemed to be leading the investigation into Jimmy Powell's murder and the NHI killer case.

But Dexter uncovered shocking evidence that showed Spencer was actually the one who killed Jimmy and kidnapped his own son, Nicky Spencer. Dexter tried to tell Harry the truth, but his father refused to believe that his old friend could be a criminal. This disagreement created even more tension between them.

By the end of the episode, Dexter's suspicions turn out to be right. Spencer set up a shootout with suspected drug cartel members, using it as a distraction to cover up his crimes. His actions showed that he was not just a corrupt cop but also a murderer who was using his position to manipulate the system for his own gain.

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Dexter: Original Sin season 1 episode 8: Captain Spencer turns out to be a killer

Dexter Morgan as seen in Dexter Original Sin (Image via Paramount Plus)

At first, Jimmy Powell's murder and Nicky Spencer's disappearance were just speculated to be an act of revenge on those who punished cartels. However, in episode 8, it is revealed that Captain Aaron Spencer was behind both. He killed Jimmy and kidnapped his own son, Nicky, keeping him asleep with sleeping pills.

To cover his tracks, he blamed the crime on drug cartels, tricking the Miami police into believing they were responsible. Dexter, who refused to ignore his gut feeling, secretly followed Spencer and saw him giving a bag and money to a young man. Later, the police received a tip that Nicky was at a cartel stash house.

Aaron Spencer, as seen in Dexter: Original Sin (Image via Paramount Plus)

Spencer and his officers stormed the house, leading to a violent shootout where several cartel members were killed. However, Dexter found the same bag he had seen Spencer hand over earlier. This proved that Spencer planted Nicky's bloodied shirt at the scene to make it look like the cartels were involved.

While Spencer's true motives were still unknown, it was clear he was using his son's kidnapping as an excuse to go after drug cartels. His past connections with these criminal groups raised the question of whether this was a personal revenge or part of something much larger.

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Dexter: Original Sin season 1 episode 8: Harry found someone from the past

Brian Moser, as seen in Dexter: Original Sin (Image via Paramount Plus)

While Dexter was busy trying to prove that Captain Spencer was guilty, Harry Morgan and María LaGuerta went to Tampa to investigate a suspect in the NHI killer case. Their lead, Paul Petrie, turned out to be useless as he had been murdered three weeks before the Miami killings.

However, while searching through his records, they found a list of his patients, including Brian Moser, a name that completely shocked Harry. Brian was Dexter's biological brother and the son of Laura Moser, who was once Harry's partner.

While reading Brian's file, Harry discovered that his past affair with Laura was mentioned in the psychiatrist's notes. Knowing that this information could ruin his reputation, Harry destroyed the evidence to keep it hidden. But learning this left him deeply unsettled.

To make things worse, one of the NHI killer's victims was actually Brian's nurse, making Brian a possible suspect in the case. This discovery left Harry in a difficult position as not only did it threaten to reveal his secret past, but it could also bring him face-to-face with a dangerous truth that might even connect to Dexter's dark side.

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Other highlights of Dexter: Original Sin season 1 episode 8

Gio and Deb as seen in Dexter: Original Sin (Image via Paramount Plus)

Besides the shocking revelation about Captain Spencer and Brian Moser, this episode also focused on Debra Morgan's troubled journey. She had been enjoying time with her new boyfriend, Gio, and was drawn to his luxurious lifestyle.

However, during a trip to Bimini, she noticed a mysterious box being loaded onto his yacht. Sensing her suspicion, Gio distracted her by giving her a diamond bracelet, but the moment left her feeling uneasy.

As Debra's doubts grew, Dexter tracked her down after finding out from Gio's fiancee that she was being lied to. He arrived just in time to get her out of what could have been a dangerous situation, bringing her back home to Miami. Her brief escape from reality ended in heartbreak, forcing her to question what kind of life she truly wanted.

Meanwhile, Dexter's relationship with Harry continued to fall apart due to the latter's refusal to believe that Captain Spencer was guilty. This growing tension between them pushed Dexter further down his dark path, shaping him into the serial killer fans know from the original series.

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Fans of the franchise can watch Dexter: Original Sin season 1 episode 8 on Paramount + Showtime.