Ramon's career may be in jeopardy due to his obsession with Oscar's killer. Meanwhile, Dexter does a great job in keeping Ramon off balance by manipulation. Deb refuses to "be a rat" after Internal Affairs presses her to come up with more dirt on Quinn. Also, Rita and Dexter decide it's time to tell the children about her "condition," and Angel's quest for companionship nearly gets him in deep water.

Dexter angers Miguel when he says no to his latest offer, who's unsure the next target lives up (or down) to Harry's Code. Meanwhile, an elderly, deathly ill Camilla asks Dexter to kill her, insisting she would never ask a friend to do something against his conscience. Also, Rita discovers that Sylvia believes her husband Miguel has had an affair; and Anton is told he is bait to get at Skinner.

Dexter undertakes to teach Miguel the Code, but doesn't realize he's whetting his partner's thirst for blood. Meanwhile, Debra is one step closer to finding the Skinner but a secret revealed about Anton sends him packing.

Miguel and Dexter's friendship is impacted when Rita confronts Miguel about his alleged infidelity. Believing Skinner has abducted Anton, Debra pulls out all the stops to find him

A series of chess-like moves ensues when Dexter and Miguel vie for the upper hand, with Miguel winning Rita's affection by presenting her with a lavish wedding gift. Elsewhere, Debra wonders if her relationship with Anton is worth the trouble.

While preparing for his big wedding day, Dexter has to figure out a way to remove Miguel from his life for good. In the meantime, Rita has troubles of her own, when Syl reveals that Miguel has been seeing one of his old flames. Debra finds a new clue that brings her even closer to catching the Skinner.

It is the day before Dexter's wedding and Dexter must deal with two people targeting him, while preparing for his special occasion. Meanwhile, Angel tells Deb he's put her in for a promotion, but after he finds out some information her shield may be gone before she gets it.

Six months after the season finale, Dexter is now living with three kids and a wife in a new home. Along with his new son Harrison, the complexities of being a suburban father of three is making it difficult for Dexter to concentrate on his work. His lack of sleep leads him to let a murderer walk by bringing the wrong documents to court and causes him to get into a car crash. Now retired Agent Lundy has returned to finally capture the mythical "Trinity Killer" who has arrived in Miami.

Suffering from amnesia following his car crash, Dexter begins searching for Benny Gomez' lost body, with a helping hand from Harry. Meanwhile, Debra struggles with the return of her former lover while Quinn tries to juggle his personal and work life. Meanwhile, Trinity begins stalking his next chosen victim.

Dexter is hampered by his neighborhood's increased vigilance due to vandalism, his temporary inability to drive himself anywhere, and his admiration for the killing technique of the artful Trinity Killer.

Dexter gets some much-needed R&R time with Rita and the kids out of town, leading to his stalking of a new victim until he unexpectedly begins to empathize with his target, a cop that murdered her family.