The episode begins with some Dexter/Prado buddy time: pizza, beer, sports, etc. Eventually Prado suggests another victim to Dexter, a former football player named Billy Fleeter who has killed several people to help settle his gambling debts. The difference this time is that Prado wants to be the one doing the deed.
The next morning we see Rita his having lots of trouble with the stress of pregnancy, the upcoming wedding and starting a new job, snapping at Dexter over just about everything. We see the relationship between Debra and Anton is progressing, with the two having moved to the "sleepover" stage of the relationship.
Angel and Gianna have also "done the deed," with Quinn and Debra telling him she will now heavily scrutinize his every action.
Dexter and Prado do some recon on Fleeter at a local casino. Dexter starts to let Prado in on his methods, telling him several aspects of the "code." Debra finds out from Anton that was never on the books as a C.I., that Quinn always paid him in cash. Wolf tells Maria that Prado has been giving her a lot trouble recently, and the two make plans to attend a police function of Maria's together.
Following-up on Debra's break from a few episodes back, Homicide has brought a bunch of tree-trimmers into the office for questioning. One of them, a Mr. King, tells Debra and Quinn that one his employees, Mario, killed somebody with a knife back in Nicaragua.
Quinn tells Debra that Anton was never officially an informant, that his arrest record was never filed. That Anton had taken an unnecessary risk as bait in the Freebo case infuriates Debra, and Quinn figures out that she is involved with Anton. Debra says she plans to tell Anton the department had been illegally manipulating him, and repeats to Quinn the allegation she heard from Amado that Quinn was responsible for the death of a cop.
Dexter and Prado break into Fleeter's house. Dexter finds a likely murder weapon baseball bat with blood traces and discovers via a gambling ledger that Fleeter is down $30,000.
Debra tells Anton the news about his non-existent criminal record and the two make plans to celebrate at breakfast the following day.
The bat blood ends up being a match to one of Fleeter's victims, so Dexter and Prado move forward with the plan. They purchase supplies (including a knife for killin') and put down the plastic in a casino supply storage facility.
Wolf and Maria go for drinks after the police function. It's clear both that Wolf is kind of a party girl and Maria needs to relax and improve her social life.
Dexter and the dark hat-and-shades-wearing Prado make contact with Fleeter at a casino bar. As they move to follow Fleeter and take him down, a man recognizes Prado. This freaks out Dexter, who immediately wants to shut the operation down. They decide to make a decision the following day.
Anton stands up Debra at breakfast. She calls Dexter, who has just seen in the paper another man has been bludgeoned to death (Fleeter's M.O.), and the two meet at a jewelry store so she can help Dexter pick out wedding bands. Debra suggests he buy Rita an engagement ring and expresses concern to Dexter that Anton may have bailed on her because he found out he's not an informant.
While waiting to pick-up Mario, Debra asks Quinn about Amado's claim that he got another officer killed. Apparently Quinn and Amado were partners in Narcotics, and a drug addicted cop they worked with committed suicide. Amado blamed Quinn because he knew about the guy's drug problem and didn't report him.
After Debra and Quinn bring Mario in for questioning. Angel, swamped with work, makes an incredibly awkward dinner cancellation call to Gianna.
Dexter and Prado meet, with Dexter now opposed to the killing. The two dance around Dexter's murdering history and each other's issues with their fathers. Prado said he feels some of the same "darkness" as Dexter, and wants to "let some of mine out too."
In the interrogation room Mario admits to stabbing but not killing a cab driver who touched his sister. He denies any knowledge of the skinner murders and when threatened with deportation by Debra and Quinn is furious that he might have to leave his American-born son. That all changes when Quinn brings up the allegations made earlier by King. Mario seems terrified of King and all of a sudden is perfectly willing to leave the country without his family.
Debra shows up at Anton's club and finds out he never showed for his gig that night.
Dexter and Prado grab Fleeter at his place, taking him back to the room. Dexter passes the killing duties to Prado, who seems to take to the moment like a fish to water. After saying they represent "justice," Prado plunges the knife into Fleeter's chest. "How do you feel?" Dexter asks a glassy-eyed Prado. "Fantastic," comes the answer from Prado, who leaves Dexter to manage the clean-up.
Debra goes to Anton's apartment, finding the front door unlocked and the place empty. She walks back out the front door, noticing with horror that the trees near the building have recently been trimmed. Is Anton the latest skinner victim?
Dexter returns home, giving Rita the brand-new engagement ring. She apologizes for her hormone-fueled actions saying it feels like she has a monster living inside of her. "Maybe I can help you out with that one," Dexter says.
Our last scene is Prado knocking on an unknown front door. The camera turns and we see that it's defense attorney Wolf. Prado moves inside the room and towards her as the screen fades to black.