At the scene of a car accident, Dexter sees Zach Hamilton photographing the wreckage. Dexter isn't sure if Zach murdered Norma but he knows he will find out soon if he keeps following Zach. Dexter follows Zach to Dr. Vogel's home. Zach's dad hired Vogel because of her reputation of working with psychopaths. Dexter is worried about Vogel: the last killer she worked with ended up kidnapping her and attempting to kill her. She acknowledges that it is a job hazard. Vogel asks Dexter to talk to her if he intends to kill Zach.
Deb hands Vince all of the information she could find on his daughter. She owes a lot of money, leading him to be suspicious of her motives. She tells Vince to just wait it out until it's obvious that his daughter is just looking for money. Deb's boss, Jacob Elway, wants her to investigate his sister's boyfriend. He implies that Deb must work this case or be fired.
Dexter helps his son, Harrison, work on a puzzle in their living room. Jamie reminds Dexter not to forget about her upcoming birthday party. She says Cassie will be there. Dexter refuses to admit that Jamie is a good matchmaker, even though Dexter has a date with Cassie that night. Dexter is called into work and leaves Harrison to finish the puzzle himself.
When Dexter arrives at the bloody crime scene to photograph the body, he spots Zach near the crime scene, also taking pictures. Dexter confronts Zach about taking pictures of crime scenes and allows him to cross the yellow tape. Zach has never been this close to a crime scene and is excited to take pictures up close. Dexter opens up to Zach about the murder in the hopes that Zach will open up to him. Zach makes suggestions about precautions the murderer could have taken to avoid getting caught. Dexter still isn't sure if Zach is the one who killed Norma. He asks Zach to call him when he prints the pictures.
On their date, Cassie asks Dexter about his interests and passions. Dexter has a hard time coming up with ideas, because most of his free time is spent hunting serial killers. Deb and Jacob scout his sister's boyfriend. Deb volunteers to talk to the boyfriend and see if he hits on her.
Dexter visits Zach at his studio to see the crime scene photos Zach took. Zach says he forgot it was a crime scene and feels like the murdered woman spilled the blood just for him. Dexter asks about a picture of a woman that's lying out. Zach crumples it up, says it's nothing, and tosses it into the garbage. Zach receives a phone call and says he has to leave right away.
Deputy Chief Tom Matthews asks Lieutenant Angel Batista why he hasn't chosen a new sergeant yet. Angel lists the reasons he has for choosing both candidates but Tom doesn't want to hear it. He tells Angel to make a decision by the end of the day.
While eating steak, Dexter and Deb discuss Vogel and the mystery surrounding her. Before leaving the house, Jamie tells Dexter that Harrison lied about hiding the TV remote. Deb says he shouldn't be worried about his son lying at such an early age.
Angel calls Quinn into his office to tell him that Miller will be the one promoted to sergeant. Quinn asks if it's because he didn't solve the murder of Norma but Angel says it's more than just that. Quinn leaves the office and runs into Dexter. He tells Dexter to give him everything he can that points to Zach murdering Norma. Dexter says that there is nothing that points to him, figuring that if Quinn is stalking Zach, Dexter can't follow him. Dexter tags along with Quinn.
Dexter and Quinn stake out Zach, who is taking pictures of women doing yoga. Quinn talks about Deb, and Dexter regrets leaving the office. One of the woman doing yoga is the woman who was in the photo that Zach crumpled up. Dexter knows that Zach's stalking her but Quinn hasn't caught on.
Going undercover, Deb attaches a hidden microphone to catch Jacob's target cheating on his sister. The target invites Deb up to his room and she agrees to go. At the elevators, Jacob runs up and punches the target. Jacob tells him to break up with his sister or she will be sent video proof.
Dexter reasons that if Zach likes to take photos of his victims before killing them, then he must also take photos afterward. Dexter breaks into Zach's office to look for photos of Norma's body. Dexter finds a USB key with photos of Norma after she died and also a photo of Zach with the murder weapon. Dexter brings the photos to Vogel. She brings up the idea of teaching Zach the code, the same code that Dexter was taught that keeps him from killing innocent people. Dexter says Zach is planning to kill a second innocent and for that he deserves to die.
At Jamie's party, Dexter sees Cassie with another man. Jamie tells him he should make a move fast if he likes her. Dexter goes to get a beer first and sees Vince gives his daughter a check for $5,000. He knows she needs financial help but that's all that he can give. She asks how he knows she needs help and he admits to doing some research on her. He just wanted to be sure she wasn't after his money. She gets upset that Vince would think she only wanted money. Jamie thanks everyone for coming and congratulates Quinn for being promoted to sergeant. Her brother, Angel, apologizes for not giving Quinn the job. Dexter talks to Cassie, and she introduces him to Oliver. He leaves to go check on Harrison.
Jacob's sister broke up with her boyfriend and blames herself for it. Jacob feels terrible for being the cause of her pain, even if she will be better off in the long run.
Dexter, putting his son to bed, asks why Harrison lied about the TV remote. Harrison apologizes and said that Dexter lies, too. He pulls out his toy dog and says he saw Dexter throw him away but said it was lost. The dog is still covered in blood stains so Dexter tells him he can keep it as long as it's under the bed.
Dexter believes Zach deserves to die and drives to his office looking for him. Zach's car is there but he isn't. Dexter finds the deed to a cheap car on Zach's desk. The one mistake Zach made with Norma's murder was that his red Porsche was spotted. Tonight, Zach is going to kill the woman he has been stalking. Dexter drives to the woman's workplace. He finds Zach in a car waiting for the woman to get off work, and Quinn still following Zach. Dexter calls Jamie and gets her to call Quinn, who leaves to go see Jamie. The woman that Zach is stalking is his father's new mistress, just like Norma. Zach doesn't go after the woman though, he sneaks up on his father. Before he gets too close, Dexter drugs Zach and drags him away. Quinn spots Dexter and thinks he is keeping an eye on Zach. Dexter brings Zach home.
Zach is plastic wrapped to Dexter's table. Zach feels he has no choice but to kill his father. The father is making the mother drink herself to death with all of the affairs. Zach thought if he killed Norma it would stop, but he thinks that he must kill his father to make it stop. Zach can't resist the urge to kill, he felt a huge release of something horrible inside him. Zach tells Dexter to kill him or he will be forced to continue killing. He's only told Vogel this secret. Dexter decides to let Zach live: he wants to teach Zach the same way Dexter was taught.
Dexter and Deb discuss the trouble they have with relationships now, which is that they both can't relate to normal people. Dexter tells Deb about his new intern. Deb feels woozy and passes out. Dexter goes to help her but he feels dizzy, too. Hannah McKay walks in from outside and asks Dexter if he remembers her.