Killer Instinct

Lia is frustrated after finding out that their adventure at Colonial University was pointless. When Cassie offers to share a tub of ice cream with her, Lia takes her to the roof of the house to eat it together. Cassie understands that Lia is hurt that Dean is shutting her out because he is the only person she trusts. After Lia shares an anecdote about her sibling-like relationship with Dean, Cassie shares the fact that Sterling was one of Redding’s victims. 

They then watch as a car enters the driveway; Sterling and the director emerge from the vehicle. From their vantage point, Cassie and Lia overhear a tense conversation between Sterling and her father. The director admonishes his daughter for trying to keep Dean and the Naturals away from the case, but Sterling argues that they should be protected. She also reveals that she had a conversation with Redding by herself, which angers the director. Before they enter the house, they mention the “Nightshade case.” From what Cassie and Lia can hear, it is an old case involving an incident with an FBI agent named Scarlett Hawkins, who was a friend of Sterling’s. Scarlett was murdered during the investigation, which was one reason Sterling left the FBI prior to returning to evaluate the Naturals program.

Cassie and Lia realize that Sterling has the teenagers’ best interests at heart. They also understand that Scarlett must have been Judd’s daughter, which explains why he and Sterling are so close.

After Lia goes back inside, Cassie spots Dean sneaking out and follows him. She apologizes for investigating Redding behind his back but argues that Redding is trying to isolate Dean from his friends to keep him for himself. Dean tells Cassie that he is planning to go to Broken Springs, his hometown, to talk to a woman named Trina Simms. He recognized her from Redding’s visitors log and wonders why she appears so obsessed with his father. Cassie, however, convinces Dean to wait until the next morning and loop the others in.

The next day, Dean and Cassie tell Lia, Michael, and Sloane about Dean’s intention to go to Broken Springs. Together, they decide that he, Michael, and Cassie will drive there while Lia and Sloane provide a distraction. Once in the car, Cassie, Michael, and Dean discuss the case and their plan to question Trina. They agree that they will talk to her together.

Dean, Cassie, and Michael are greeted by Trina’s son, Christopher, when they arrive at her house. He seems tense and rather hostile and initially tries to send them away. However, Trina lets them in once she realizes that Dean is Daniel Redding’s son.

Trina and the three teenagers sit down to talk about Redding. Trina believes that she is in a relationship with him and appears excited to be hosting his son. Cassie, however, knows that Redding is only using Trina. When Christopher angrily tries to kick the teenagers out and grabs Cassie, Dean threatens him. However, they eventually leave anyway, as Trina does not appear to know anything relevant to the case.

As they get back to the car, Michael gives Dean his keys and lets him drive them to his old house. While there, Dean briefly reminisces about his mother, Marie, who abandoned him when he was younger. Michael tells Cassie that good memories can hurt more than bad ones and urges her to sort out her complicated feelings for Dean.

Judd and Sterling are waiting for the teenagers when they come back to the house. After they left Broken Springs, Christopher reported Dean’s visit to the local police, so Briggs is currently handling the situation there. Sterling orders Michael and Dean to bunk together and keep an eye on each other at all times. She argues that, should another victim be murdered, Dean might now need an alibi. Cassie suggests that Christopher could be a suspect just as Sterling receives a call: Trina’s body was just found, and her son cannot be the killer since he is currently giving a statement to Briggs. Before she dismisses the teenagers, Sterling also puts an ankle tracker on Cassie, as she promised to do if the young girl left the house again.

The killer gleefully reminisces about torturing and murdering Trina Simms.

Cassie is frustrated that all their leads have been proven wrong so far. As she and the others brainstorm everything they know about the victims, Dean suddenly realizes something. He calls Briggs, who is currently at the scene of Trina’s murder, and asks him to look for any signs of games or trinkets. When Briggs finds a playing card in the victim’s pocket, Dean realizes that his father is sending him a message. This means that they are not looking for a copycat but a partner.

The teenagers explain their findings to Briggs and Sterling. Since Redding wants to own his son and mold him into his image, he wants Dean to know that he is behind the killings. Redding has been pulling the killer’s strings and orchestrating the murders from behind bars, which leads Cassie to believe that he has an apprentice rather than an accomplice. As a result, the killer may be as young as 17, Dean’s age.

The next day, Briggs gives the teenagers recordings of all of Redding’s interviews. Lia, Michael, and Cassie are tasked with watching them and seeing if they can learn anything of value. Meanwhile, Dean and Briggs go back to the prison to talk to Redding again. As for Sloane, Sterling asks her to work on a geographical profile of the killer. Lia, Michael, and Cassie then watch three different interviews. The first takes place after Emerson Cole’s murder, when Briggs first came to ask Redding for information. Redding agreed to help, but he only wanted to talk to Dean. The second interview is the one that Cassie saw at the prison. However, after she and Sterling were ushered away, Redding revealed that Dean branded Sterling when she was Redding’s prisoner.

Sterling, who is watching the tapes alongside the teenagers, confirms that Redding is telling the truth. However, she then plays them the last recording, which shows an interview between Redding and Sterling. In it, Sterling taunts Redding by revealing that she and Dean came up with a plan to escape together by having Dean hurt Sterling and thus earn Redding’s trust. They were successful, which angers Redding. 

After these revelations, Cassie meets with Sloane, who updates her on the geographical profile. The data points to the UNSUB’s comfort zone being centered on the prison housing Redding. Finally, Briggs and Dean return from their visit. They are frustrated because Redding refused to speak to them unless Dean brought Cassie with him. Briggs, however, announces that they found DNA evidence on Trina’s body.

The killer seemingly admonishes themselves for leaving evidence behind. However, they are in the middle of ambushing a new victim. They catch the unnamed person unaware and knock them unconscious before getting ready to kill them.