Dexter Morgan assists detectives Batista and Doakes in investigating the murder of an undercover officer. Debra discovers a piece of evidence in the Ice Truck Killer Investigation that helps her get ahead.
Dexter has taken a little time off to take his boat out and relax. He watches some teenagers messing around and notes that playing comes easier to them than to him. He goes back to his apartment and Debra brings him bagels and they talk about the Ice Truck Killer case. After she leaves, Dexter looks over the doll parts that the Ice Truck Killer gave him and notices that the doll's hands have differently painted fingernails. Dexter attends court to give blood report testimony against a criminal. While leaving, he notices a crying family and sees what he describes as an "opportunity". He enters a court case where Matt Chambers is being trialed for manslaughter, for drunkenly running over eighteen-year-old Alexander Pryce with his car. The court is adjourned and Dexter travels to a crime scene just outside Miami.
Dexter examines the body and tells LaGuerta that it originated from the Westbound Causeway, after which he notices that the victim has something in his mouth. After a death rattle spurts blood into his face, Dexter removes a piece of human flesh from the victim's mouth. Later, back at the station, Debra tells him about her new boyfriend, Sean, a mechanic, and Dexter offers to meet them for lunch along with Rita, which Debra skeptically agrees to. After finding out that the man killed under the causeway was a police officer named Ricky Simmons, James Doakes and Lt. LaGuerta go to make a next-of-kin notification when they find Kara Simmons shot in her home. The whole team gets to the house and Dexter takes snapshots of the scene, where he notices an inconsistency in the blood and finds a cell phone.
Dexter then goes around Rita's house and tells her about his double date plan, telling her that it was Debra's idea. He goes home and is woken up when Debra phones and tells him that she has found the Ice Truck. She calls the team in on it and they find human fingertips inside an ice block in the back compartment. The truck is searched and found to be spotless. Later, back at the MMPD (Miami Metro Police Department), they melt the ice and find that the fingertips have differently colored fingernails. The skin found in Ricky Simmons' mouth is found to be Norberto Cervantes, whom Doakes and his team apprehend while he is meeting with Carlos Guerrero. The Matt Chambers case starts up again and he is put on the stand and tells them that he reported the car stolen hours before Alexander was hit by it and that he has been sober for several months. Meanwhile, Doakes and LaGuerta interrogate Cervantes who tells them that Ricky's wife Kara was sleeping with another man. Doakes punches him. María takes a blood sample from his arm to confirm that it was him.
Reconstructing the scene of Kara's shooting, Batista and Dexter find blood far from the actual scene which turns out to be a 100% match for Cervantes. María stops Doakes from doing anything about it and tells him that they should look at the big picture and try to get Guerrero. Dexter stalks his potential victim Matt Chambers to a bar and speaks to him and finds out that he has moved around from place to place his entire life and takes a whiskey glass to check prints. He lifts the fingerprint off the glass and runs it through a database to find that Chambers has killed people while driving drunk in Santa Fe, New Mexico and South Boston under the aliases Matthew Brewster and Matt Rasmussen. Dexter then prepares his kill room.
Doakes visits Kara Simmons in the hospital and María notices that he is being overly caring. Dexter then attends the double date with Rita, Debra and Sean. When Rita notices the apparent ease of Debra and Sean's relationship, she starts to feel insecure and Dexter notes that he is lost for words to comfort her with. Norberto Cervantes is killed in jail by a man impersonating a police officer. Later, Rita starts to kiss Dexter but pulls away from him when it starts getting too sexual. Dexter tells her that he is fine with them not having sex until the time is right for them and she tells him that he is a truly decent man. Dexter examines the dead fingertips and discovers that they were removed post-mortem, Debra tells him that the prostitute's name was Cheri Taylor. Debra, at the command of Captain Matthews, goes to see her lieutenant and Matthews and is told by LaGuerta that she is being promoted to Homicide. Later, María goes to Doakes and tells him that Kara Simmons died of a heart failure and voices her suspicions that he was sleeping with her. He confirms it and he tells her that she was going to ask Ricky for a divorce. As a personal favor to him, she refrains from taking him off the case because he tells her that no one is more motivated than him to get justice.
While stalking Matt Chambers, Dexter gets a text message from Debra to celebrate her promotion and she tells him that she dumped Sean because he was in fact married. Dexter thinks back to the time when Harry was late picking him up because he was angry at the decision to let the man who killed his partner walk. He sees Guerrero going to the toilet and he contemplates killing him but decides against it. In the final scenes, Dexter has kidnapped Matt Chambers and gets him to confess to killing Alexander Pryce. He then kills him by stabbing him in the heart. He empties the man's remains into trash bags and returns home after throwing the body parts into the ocean. He finds the doll head back on his fridge again and opens his freezer to discover that the doll parts are missing and that the Ice Truck Killer has broken into his apartment for a second time.
- After the scene where Debra is transferred to homicide, Batista and LaGuerta have a short conversation in the kitchen in Spanish without subtitles. The rough translation of the scene is as follows:
- LaGuerta: How's Nina and your daughter?
- Batista: They're marvelous.
- LaGuerta: You know they need you too, eh?
- Batista: (Small nod, says nothing)
- LaGuerta: Angel, go home.
- Michael C. Hall as Dexter Morgan
- Julie Benz as Rita Bennett
- Jennifer Carpenter as Debra Morgan
- Erik King as James Doakes
- Lauren Vélez as Maria LaGuerta
- David Zayas as Angel Batista
- James Remar as Harry Morgan
- Geoff Pierson as Thomas Matthews
- Sam Trammell as Matt Chambers
- Rudolf Martin as Carlos Guerrero
- Cristos as Norberto Cervantes
- C.S. Lee as Vince Masuka
- Richard Gunn as Sean "The Mechanic"
- Lisa Kaminir as Prosecutor
- Christina Robinson as Astor Bennett
- Daniel Goldman as Cody Bennett
- Maureen Muldoon as Kara Simmons
- Devon Graye as Teenage Dexter
- Keith Pillow as Lawyer
- Brandon Morris as EMT
- Roger Hewlett as Mr. Pryce
- Alex Schemmer as Alexander Pryce
- Andrew Hawkes as Officer Wilkins
- Roxanne Beckford as Reporter Candice DeSallee
- Nine Onuora as Uniform #1
- Camilla Banus as Girl Swimming
- Wing Armstrong as Medical Examiner Munoz
- Jason Bartley as Crime Scene Officder
- Rob Goodman as Ricky Simmons
- Erik Joseph as Police Officer