Miguel introduces Dexter to former football player Billy Fleeter, a debt enforcer who kills other gamblers to pay off his own debts. Dexter is initially hesitant when Miguel suggests that Dexter teach him how to murder Fleeter, but the two go to a casino where Dexter tries to explain his deceased father Harry's "code" to Miguel. They later break into Fleeter's house and, although they find the murder weapon, Dexter says that they need evidence proving that Fleeter has the incentive to kill again. Dexter finds a ledger recording each of Fleeter's bets and he returns with Miguel to the casino where they prepare an unused storeroom for the murder. They arrange to kill Fleeter that night, but somebody recognizes Miguel in the casino and Dexter calls off the plan. Dexter is angered when Miguel criticizes Harry's code, but he agrees to go ahead with Fleeter's murder after Miguel mentions that he severely beat his abusive father and found it to be one of the most satisfying moments of his life. They drug Fleeter and take him to the casino storeroom. Miguel stabs and kills Fleeter, telling Dexter afterwards that he feels "fantastic". While cleaning up the crime scene, Dexter has a vision in which his father tells him that sharing the code was a mistake and that Dexter is now responsible for Miguel's actions.
Debra finds a bag of marijuana hidden in a cereal box in Anton's apartment and asks her partner Joey Quinn about Anton's previous charges for drug possession. Quinn tells her vaguely that it can be found on file, but when she asks Anton for his informant number, he tells her that he has none. She discovers that he had been working for Quinn unofficially and that he is not legally obligated to disclose any information to the police. After she tells him that he no longer has to work as an informant due to a "clerical error" in the filing of his report, he disappears. Debra and Quinn continue to work on the case of serial killer "The Skinner". Believing that The Skinner may be a tree-trimmer, they bring in a number of them for questioning; one contractor, George King, tells Debra about one of his suspicious workers, Mario Astorga. When Mario tries to run from them, Debra and Quinn arrest him and he pleads to be sent back to Nicaragua at the mention of King's name. Debra later visits Anton's apartment and realizes that he has been taken by The Skinner, who recently trimmed the trees.
Dexter's fiancée Rita is unusually temperamental due to her pregnancy hormones. She complains to Miguel's wife Sylvia Prado that Dexter refuses to help with the organization of their upcoming wedding. Despite having told Dexter that she did not want an engagement ring, Debra and Dexter choose a ring for Rita, and she apologizes for her behavior. Meanwhile, defense attorney Ellen Wolf tells her friend Lt. María LaGuerta that she thinks that Miguel is going out of his way to make her job harder. At the end of the episode, after killing Fleeter, Miguel makes an unannounced visit to Ellen's house.
- Casino scenes take place at Hollywood Park Casino in Inglewood, Ca.