Dexter and Killer del camion frigo have a final confrontation. After kidnapping Debra, Rudy is in the final stages of his plan to reunite with his long-lost brother. Doakes and LaGuerta investigate the case, and Doakes begins to suspect that Dexter is involved. Meanwhile, Paul Bennett tries to convince Rita that Dexter is not who she thinks he is.
Dexter frantically searches for clues for Debra's whereabouts when Rudy, finally revealing himself as the Ice Truck Killer, abducts her and forces Dexter into a series of mind games to find her. Dexter returns to his apartment in hopes of finding clues left there by Rudy, he then sees his "new" screen saver playing the song "Born Free" and suspects that Rudy might be keeping Debra at the cargo container where his mother was butchered and where Harry found him. At the hospital, LaGuerta and Doakes pay a visit to Batista who is being treated for the stab wound he endured earlier in hopes of finding leads to the Ice Truck Killer, they suspect that Rudy Cooper might indeed be the killer and could have kidnapped Debra as well. As Dexter frantically searches for the container, he is unexpectedly visited by LaGuerta and Doakes, Doakes accused of Dexter knowing something as he was skulking in the lab ordering secret blood tests from Batista's collar which he was forced to reveal to be Rudy's. Rita is contacted by the imprisoned Paul who tells her that Dexter framed him for his drug possession charge. Meanwhile, LaGuerta locks horns against her replacement Lt. Esmee Pascal, who's even MORE officious and pompous than her or Captain Matthews, and who hampers the case by ignoring key evidence to further advance her own personal career. Dexter sneaks into the shipping yard to find the container "CBAN-348 9" and had a brief flashback of Harry finding him as a child, as Dexter nervously opens the container, he found nothing but bananas in it. Doakes caught Dexter by surprise and the two engages in a brief brawl until security kicks them both out. Meanwhile, as Rudy is driving Debra to an unknown location, Dexter enters Rudy's apartment where the police has been finding evidence linking him as the Ice Truck Killer, including his Kill Room. Rita is visited by Paul's Narcotics sponsor Bob Hicks who tries to convince Rita that Paul had been framed. Dexter searches the apartment and finds a record player playing "Born Free" and a Barbie doll with "Home Sweet Home" written on it. In an unknown location, as Debra struggles to escape, Rudy kicks her to the ground and sedates her. Dexter suspects that Rudy might be at his mother's house and searched through the database for her address, Rita makes an unexpected visit, but it was brief as Dexter explains that Debra might be in trouble. At the hospital, Batista watches the news regarding Rudy who's true identity is still left a mystery as his prints weren't present at the criminal database, but after hearing the nurse about how dangerous psych patients can be, Batista calls the department to run a test on Rudy's prints on the psych mental institution database as the suspects that Rudy might indeed be a psych patient. Dexter arrives at his mother's house, he had a flashback of his childhood and Rudy appears revealing himself to be his biological brother Brian, Dexter marches straight into the house in search for Debra but was sedated by Brian. Batista returned to the station handing LaGuerta the file revealing Rudy to be Brian Moser who was institutionalized for anti-social personality disorder but was released at the age of 21 after it was believed that he had been cured of his mental disorder, but Lt. Pascal believes that Brian might be at 20 miles off the coast by boat, this lead to LaGuerta and Pascal in having a brief confrontation with each other. Brian tries to reconnect with Dexter by revealing his past to him and tries to convince Dexter to kill Debra who he had wrapped in plastic in a similar manner to Dexter's victims. Dexter refuses and tackles Brian, Doakes and several officers arrived at the scene but Brian escapes before they could capture him. Dexter tries to convince Doakes that it was Brian who called him, Doakes threatens Dexter by giving him suspension but Debra steps in and yells at Doakes to leave her brother alone. While on the way to the hospital, Debra worries as Brian is still out there and he might try to kill her again, she hugs Dexter and thanks him for saving her life. Paul contacts Rita one more time to warn her that Dexter was actually the one who set him up by telling her to find his missing shoe that might have slipped from his foot when Dexter dragged him, Rita didn't believe Paul's warning and hangs up. At the hospital, Dexter is beginning to wonder if did Harry really betrayed him because of keeping his brother's existence from him all these years. Brian later goes to Dexter's apartment, where he believes Debra is staying, and tries to kill her. However, it turns out to be a trap set by Dexter. He strangles Brian until he passes out and transports him to Brian's apartment, where he suspends him in the air, just as Brian did to his victims as the Ice Truck Killer. Brian tries to convince Dexter to set him free, telling his brother he can be free to be his true self with him. A frustrated Dexter loudly dismisses this, causing a single tear to run out of Brian's eyes. Dexter says he can't let Brian live because he knows he will always want to kill Debra. Brian continues to lecture Dexter on how he's being irrational and choosing to live a lie for people who will never really know or care about the real him instead of embracing family who accepts him. Dexter is tempted, but ultimately slices Brian's throat, telling him he can't hear anymore, while admitting Brian is right. Dexter was able to convince the police that Brian committed suicide by using the same way he committed his crimes. The next day, Dexter returns to Rita's house to make up for the previous visit, Dexter leaves for work and notices Doakes tailing him and worries that he might find out about what he really is, as Rita waves good bye at Dexter she notices the shoe Paul mentioned last night and worries that what Paul said might be true. Dexter mourns his brother's death and still wonders if what he is doing is worth it, as he and Debra walk to the crime scene, and he fantasizes about everyone cheering for him for what he does. Dexter accepts for what he is and considers himself the same as everybody else as well as their darkest nightmare.
- Michael C. Hall: Dexter Morgan
- Julie Benz: Rita Bennett
- Jennifer Carpenter: Debra Morgan
- Erik King: James Doakes
- Lauren Vélez: María LaGuerta
- David Zayas: Angel Batista
- James Remar: Harry Morgan
- According to the original script, the title of the episode used to be "Black Heart Optional". The relation to the episode is the choice between Dexter choosing to kill Debra or spare her, then ultimately killing his brother Brian while expressing his true emotions for the first time after his death.
- In addition, the title refers to a line spoken by Dexter (imitating an invitation by his "friend") on Page 292 of Darkly Dreaming Dexter: "The honor of your presence is requested at the vivisection of your sister. Black heart optional".