When a local convict claims he has new information regarding a 15-year-old crime spree, Miami Metro sets out to unearth new evidence on the case. Debra attempts to cure Dexter of his killer tendencies. Meanwhile, the Mike Anderson Investigation leads to the Ukrainian Mob and a vengeful Louis won't stop meddling with Dexter's life.
Dexter is trying to calm Debra down following his second "big reveal," that he is a serial killer. He tells her he's been killing since he was 20 and only kills certain kinds of people. Dexter explains his dark passenger and his code. Even knowing the type of people Dexter kills Debra isn't sure what to do. She punches Dexter in the face and storms out.
At the office, Debra looks up the Bay Harbor Butcher. She also reads that serial killers have a type of addiction and will continue to kill until caught.
Since Debra found the Ice Truck Killer hand in his apartment, Dexter realizes it can't be in evidence. While he looks, a panicky Masuka walks in and tells him about the hand being stolen. Masuka says he put Louis in charge of finding it. He's relieved when Dexter says he's not going to turn him in.
At Debra's next briefing the plan is to shut down the strip club twice a day until somebody tells them something about what happened to Mike Anderson. Debra tells them a murderer named Randall (who went on a multi-state killing spree with his girlfriend) now says he has evidence of an additional victim and wants to lead authorities there to clear his conscience. Dexter volunteers for the job, but Debra assigns Masuka.
Outside the station, Debra tells Dexter she came very close to arresting him, but doesn't know what to do. Her plan is to conduct a kind of rehab for Dexter, which basically consists of him moving in and her watching him 24 hours a day.
Maria hears back from a private lab that the blood on the slide found in the church belonged to Travis. She instructs the person to keep everything very hush-hush and calls the FBI.
The guys shut down the strip club yet again and manager George Novikov (Jason Gedrick) is getting upset. Quinn hits it off with a dancer, Nadia (Katia Winter). She gives him the name of Kaja's bouncer boyfriend Tony (who didn't show up for work) and he leaves his card.
On the first night of serial killer rehab Debra instructs Dexter he'll be sleeping in her bed, while she sleeps on the couch. During spaghetti dinner Dexter says his need to kill starts with seeing blood, which eventually turns black. That night Dexter begins to research the plans of Louis' penthouse.
Quinn interviews Tony, who has little to say. But security tapes do back up his alibi for the night of her murder. Tony drops Viktor's name as the one who Kaja was with that night.
Masuka complains about the Randall case being mostly waiting around while the diggers try to find the body. Dexter volunteers to relieve him, but he needs Debra's permission. She's all set to go with him until Angel shows up with the info about Viktor, who is a member of Ukrainian organized crime.
While waiting at the dig site Dexter strikes up a conversation with Randall. Dexter asks about his change of heart. Randall says he decided to surrender.
Dexter sneaks to Louis' penthouse during lunch. While he's there he learns that Louis was the one who cancelled his credit cards. On the computer he finds several videos, one with Louis and a prostitute. He finds evidence that Louis probably framed a man in order to take control of his software company. Louis comes home unexpectedly. He sees his laptop open and Dexter pins him up against a wall, demanding to know why he's screwing with him. Louis says it's because Dexter trashed his video game. Dexter says he never wants to see him again, either at work or with Jamie.
Back at the site Debra is upset Dexter is running late. Randall notices the dispute and Dexter tells him about the boss/sibling dynamic. He asks Randall for clarification on the surrender line and he says once he stopped fighting it the anger went away.
After yet another strip club shutdown George goes back to his office to find Isaac Sirko (Ray Stevenson).Isaac clearly runs the organization and George is surprised he's in the U.S. Isaac believes George when he says he knows nothing about Viktor's disappearance.
Nadia calls Quinn and asks for a ride home from the club.
Maria has had the slides from the Bay Harbor Butcher case sent to her. She compares them to the one found at the church.
Dexter comes home and is surprised to see Louis there, hanging out with Jamie Batista (Aimee Garcia), flaunting the fact he's not scared of Dexter. Dexter thinks to himself that he needs to stop Louis.
After the ride home, Nadia flirts with Quinn without giving him more information.
Dexter injects drugs into Debra's steak that night so he can sneak into Louis' place. He sneaks up behind Louis and knocks him out with a needle. Dexter takes Louis to a location, then seems to have second thoughts. He calls Debra and tells her he's seeing the blood. She arrives and he tells her he couldn't go through with it. She thinks he took a major step by calling her. After Debra leaves Dexter simply leaves Louis on a park bench.
Isaac and a henchman pay Tony a visit. After tricking Tony into admitting that he spoke with the police, Isaac sticks a screwdriver into his right eye socket, killing him instantly.
The next day Dexter and Debra are back at the Randall dig. When Debra goes to grab some ice cream, Randall talks about the fact he never got to patch things up with Hannah, the girlfriend with whom he committed his murders. He says Hannah only sees him as a killer. Randall says the clock has run out, then steps onto the highway and in front of a truck.
- Several new characters are cast in this episode. Tony Rush, a Caucasian male with a football player's build that is a former bouncer at a Miami strip club. Wayne Randall, a prisoner serving a life sentence for homicide. And two minor characters for some small lines such as an FBI Agent and Lab Tech.
- Another character was cast for a minor role as a seductive, attractive (in a goth/punk sort of way) Naked Woman that will be featured with some nudity in a compromising tape with a male character.
- The Episode was previously titled "The Shadow Knows" however it received a title change to "Sunshine and Frosty Swirl". This is the first of two episodes to have its name changed in Season Seven, the second being The Dark... Whatever (formerly known as "Because I Want To").