The seventh episode of Jo Nesbø's Detective Hole commences with Beate phoning Harry to alert him that Martin Aminov, the middle-aged woman's son, has returned to Oslo from Prague. Harry promptly informs the team that Martin is the serial killer and is about to make his next victim. He hastens to the woman's house, where Beate is stationed. Meanwhile, Tom halts Harry and the other officers from proceeding to the location, ordering all police forces to stay away from the building. He explains that he doesn't want Aminov to realize they know he's the serial killer.
At the house, Mrs. Aminov informs Beate that she has left the door unlocked for her son. Beate panics when the downstairs door opens, but then realizes it's Tom. Elsewhere, Harry scrutinizes CCTV footage from the building and notices a star-shaped engraving on one of the apartment doorframes. He enters the apartment, hoping to catch Martin in the act of murder, but instead discovers Marius' rotting hand, which is missing a thumb.
Back at the building, Harry and the team search the storage unit and find Marius' lifeless body. Harry informs Beate that Marius was killed long before Camilla, suggesting he was the first victim. He also states that the final victim will have their pinky finger cut off that day. Meanwhile, Beate tells Harry that Tom is attempting to stall them by keeping them away from Martin.
Tom waits with both a police gun and the murder weapon in his hand. When Martin arrives, Tom lies about disarming him and asks Beate to arrest him. The tension mounts as the cat-and-mouse game between the detective and the killer reaches its climax.
Martin is swiftly apprehended and escorted to a prison cell, where he's later presented as the notorious serial killer at a press conference by the police. Meanwhile, Beate is distraught that Tom claimed sole credit for solving the case. Detective Falkeid informs Harry that Martin's fingerprints were nowhere to be found, sparking confusion and suspicion.
Elsewhere, Harry reveals to his team that he's quitting the police force and decides to celebrate his departure with something different. That night, Harry meets Tom in private, who insists that Martin is indeed guilty of the murders and enlists Harry into a committee. Tom offers Harry a drug and asks him to murder Martin, claiming it should appear as a suicide so that a criminal like him wouldn't walk free.
The next day, Harry visits Rakel's house to pick her up for the play. Oleg is thrilled to see them together. During the play, Maya questions Harry about the murders and Tom's leadership in the investigation. Rakel is surprised to learn that Harry has quit his job.
After the performance, Rakel thanks Harry for helping Oleg and reveals that her son has grown close to him. She opens up about her feelings and wonders if they can be together. Harry leaves, promising to return later.
Meanwhile, Harry visits Martin in prison. He asks Otto to start recording and secures a spare phone from his taxi-driver friend. In the prison cell, Harry handcuffs Martin and interrogates him about the four murders. Martin insists on his innocence, claiming he's being set up, but refuses to provide further details.
Harry feigns poisoning Martin, using it as a tactic to coerce a confession about his ties to Tom and the committee. Martin begs Harry to take him to a safe place where Tom cannot reach him. Meanwhile, Harry defies Tom's orders and whisks Martin away from the prison. Tom's fury is palpable when he learns of this. Later that night, Mrs. Aminov contacts Beate with a distressing request for a meeting with Martin. She reveals that her tenant, Ina, has been missing for several days, causing Beate's alarm. Furthermore, Mrs. Aminov discloses that Ina is secretly seeing someone that she knows nothing about. Tom informs the leader of the committee about Harry's actions, prompting the leader to issue a deadly order: eliminate both Harry and Martin to prevent the truth from being exposed. The episode concludes with Tom making a call to orchestrate the mission to eliminate Harry and Martin.
