Dexter is determined to take care of the Trinity Killer/Arthur Mitchell himself, at least in part to atone for the mistake he made. When Dexter learns that Christine Hill is in custody, he realizes that the police will soon be onto Arthur, so he sets up an elaborate ruse to send them down the wrong path. It all backfires and ends in another death. Arthur also learns Dexter's real name and the work he does. Meanwhile, Rita finally tells Dexter about the kiss at Thanksgiving, but isn't quite sure what to make of his nonplussed reaction. Also, Laguerta and Batista are caught kissing on a store surveillance video and Captain Matthews is set on having them both fired. They decide there's only one way to get out of he mess they've created for themselves.
Christine is interrogated by Angel about her relationship with Trinity. Meanwhile Arthur calls Kyle and asks why he has not gone to the police, and Kyle blackmails him and asks US$ 50,000; otherwise he will disclose that Arthur is pedophile. Chief Matthews calls Lt. LaGuerta and Sgt. Batista and shows them kissing each other in the images of a surveillance camera and tells that they have committed perjury and will have a meeting with Internal Affairs and they will be fired from the police force. Dexter wants to kill Trinity and seeks out another criminal to be incriminated and uses the truck driver Stan Beaudry to decoy the Miami Metro detectives. Angel and Debra find the postcards from Trinity hidden in Christine's apartment and they use them to press Christine. Dexter is summoned to be the best man of LaGuerta and Batista, who decide to get married. Christine confesses to Debra that she killed Lundy and commits suicide. Arthur follows Dexter and finds where he works.
Miami Metro is just one step away from discovering the identity of the Trinity Killer. And Dexter can't let that happen. Dexter must take drastic action to buy himself time to deal with Trinity in his own fashion. Arthur, who still can't understand why Dexter didn't simply turn him in, begins his own bloody investigation into Kyle Butler.
Dexter's worst fears are finally realized. Meanwhile, Debra is on the verge of uncovering the identity of the Trinity Killer.
- Open with Angel interrogating Christine about her relationship to the Trinity killer. She isn't talking other than to say that she never met her father.
While watching the questioning Dexter is worried Christine will eventually give up Trinity's real name and keep him from being able to mete out justice to Trinity himself. Dexter says "I'll give them a name." Dexter begins looking for a bad guy to frame.
Trinity sees on TV that "Kyle Butler" (Dexter) elected not to report him to the police. He calls Dexter and asks what he wants. Dexter responds that he want "50 grand" or he'll tell everyone who Arthur Mitchell really is.
Trinity starts looking through the 'phone book for addresses for a "Kyle Butler."
Debra is convinced Christine knows something but Quinn still isn't sure, pointing out that they are both too close to the shooting to see it objectively. They get a search warrant for Christine's apartment.
Captain Tom Matthews pulls Angel and Maria into his office and shows them security camera footage of them sneaking a kiss in a liquor store. He is going to bring them in front of a review board with the goal of having them both fired.
Dexter goes through Lundy's research and finds a one time potential suspect and prostitute-murderer named Stan Beaudry.
Trinity starts to break into a Kyle Butler's house. The man comes home and catches him. The man tells Trinity he is going to call the cops.
Dexter arrives for counseling with Rita. He is called away for a crime scene and she tells him about kissing Elliot. Dexter leaves.
Dexter goes to the scene of a murder. It is the guy who caught Trinity breaking into his house and we learn his name is "Kyle Butler." Trinity is in Miami looking for him.
In Christine's apartment Debra and Angel find the postcards Trinity sent to her from each of his murder cities. They are all signed "Daddy."
Dexter knocks out another Kyle Butler and waits inside the house for Trinity. Trinity sees the man's picture just inside the door, realizes it isn't the "Kyle" he is seeking, and does not come all the way inside.
Angel presents Christine with the new evidence that she is Trinity's daughter. He suggests that she dated Quinn to keep tabs on the investigation and shot both Lundy and Debra.
Quinn realizes that Christine has been lying to him and is furious.
Dexter goes to the shack-like residence of Beaudry, and learns that Beaudry is driving a truck near Jacksonville and won't be back until the next day.
At home Dexter and Rita discuss the kiss. He doesn't seem jealous and it bothers Rita.
Trinity cannot get Christine on the phone. He goes by her apartment and see police tape on the door.
Dexter goes to Trinity's home and obtains some DNA samples to plant as evidence.
Debra takes a stab at questioning Christine. They compare father issues, but ultimately Debra gets no new information from her.
Afterward Angel tells Debra that Christine's lawyer is demanding she be released. They think Christine might lead them to Trinity once she's released.
Without prior warning, Dexter becomes the lone witness for Angel and Maria's quickie wedding in the office.
Dexter goes looking for for Beaudry and learns via CB he is at a truck stop. On the way Trinity calls Dexter to tell him he has learned his home address was made-up and has been lying to him from their first meeting. They arrange to meet the following day.
Dexter grabs Beaudry in his truck and kills him in the back. Dexter drops Trinity DNA in Beaudry's cab and leaves a picture of Christine and some of Lundy's research info.
Christine calls Trinity from a neighbor's phone. He quickly hangs up on her.
Dexter goes to Beaudry's place and leaves Trinity's toothbrush and comb, along with his murder hammer.
Dexter returns home and sees Elliot on his front porch next door with Rita looking out the window. He punches Elliot in the face and tells him to stay away from his wife. He goes inside and Rita seems happy with what happened.
Angel and Maria tells Brass they are married. He's furious they went around the system but doesn't seem to have much of a choice but to leave them alone.
At Beaudry's place Vince finds the DNA evidence and Debra spots the hammer.
We see Trinity watching TV coverage of Angel saying Beaudry is their "No. 1 suspect." Christine calls Trinity again. The conversation ends with him telling her he is sorry she was ever born. She cries in horror.
Trinity calls Dexter from the amusement park where he grabbed the Scott kid the last episode. Dexter plans to find him there.
Christine asks to speak with Debra alone. She confesses to shooting Debra and Lundy and then commits suicide by shooting herself in the head in front of a horrified Debra.
While Dexter looks for Trinity at the amusement park, Debra calls and tells him she needs him. He leaves, and we see Trinity is now on Dexter's tail. Trinity follows him to the police station. Trinity goes inside and learns no one named Kyle Butler works for Miami PD. He snags a visitor badge to gain entrance past the cursory security, and begins casually walking around inside the station.
An emotional Debra tells Dexter she's afraid to erase Lundy's name from the "unsolved" board. The case's closure seems to bother her, but eventually she wipes the name off the board.
Trinity spots a picture of Dexter competing for the Homicide bowling team. He heads straight for the Homicide floor and walks over the room where all of the Trinity evidence is laid-out. Trinity sees Beaudry's name: "You've done me a kindness," he tells the photo.
Trinity walks through the department and locks eyes with Dexter. The two walk slowly toward one another and meet face-to-face in the middle of the room. Trinity looks down at Dexter's badge and says, very deliberately: "Hello, Dexter Morgan."