Following the death of Jonathan Farrow, Dexter obsesses over killing someone who didn't fit the Code. He feels "uncomfortable," an unusual feeling after his ritual. To make matters worse, since Farrow's assistant, Timothy Brand, was arrested after confessing to the murders for which Dexter killed Farrow, the department now considers Brand a person of interest in Farrow's disappearance.
While presenting the case in front of the rest of homicide, Debra finds that she accidentally left in a slide from a previous case, revealing to LaGuerta that she is still investigating Trinity. LaGuerta forces Debra to explain the entire investigation, including her theory that it was Trinity who shot her and Frank Lundy in order to escape detection. Dexter sarcastically (and privately) hopes that this sounds insane so that Debra will be forced to end her investigation.
Debra explains that there has been a pattern, "a trinity of victims" every year for approximately thirty years, each time in a different city across the United States. All three victims are killed in the same way and in the same order: exsanguination in a bathtub, forced to jump from a building, and beaten to death with a blunt object. "Bathtub, jumper, bludgeon," as Debra puts it. This, she explains, is why Agent Lundy dubbed this serial killer the "Trinity Killer." When LaGuerta asks if it was an FBI case, Debra says the FBI never accepted this as proof of one killer. She then goes on to say that Lundy came to Miami in order to hunt Trinity, but that she thinks he got to close, so they were both shot by the killer. To Dexter's frustration and Debra's delight, LaGuerta seems to believe the theory. He congratulates her then leaves while Quinn attempts small talk, commenting to himself that he needs to "stab something."
Elsewhere, Arthur Mitchell kneels and prays over a freshly-made coffin.
Dexter visits Arthur at his home, asking Jonah how his car is doing. When Dexter (still going by the alias Kyle Butler) begins talking to Arthur, the latter turns to his son as he is waxing the car, softly chastising him for not waxing it correctly. Dexter notes the appearance of "small cracks in the perfect family." Arthur's wife comes outside and lets him know that his clothes are ready to be packed, as it turns out he is going to Tampa for a Four Walls build (possibly to begin the victim cycle again, sooner than normal, as Dexter notices). Another "crack" appears when Arthur chastises his daughter, Becca, for not watering the flowers properly. Dexter asks when he plans to leave, which turns out to be after work the next day. Dexter takes his leave, beginning to plan how to manage that time off in order to kill Arthur.
Back at the department, Dexter looks up events in Tampa related to his job to use as an excuse on short notice to be out of town. Debra interrupts him, furious because LaGuerta took her off the Trinity case due to her being a self-reported victim of the killer. It appears that LaGuerta doesn't want Debra's emotions clouding the investigation. Dexter tries to comfort her, saying that this will free her up to "help the department in so many ways." Debra shoots back, explaining that she went from bringing in the biggest case in the MPD's history to being freed up in one day. Dexter awkwardly exits out of his search for Tampa conferences and stumbles across the perfect answer for how to be there: the East Coast Meteorological Conference.
He is instantly able to make the connection to how weather patterns such as barometric pressure and humidity can affect the integrity of blood spatter, painting this conference as a roundabout way of becoming a more efficient analyst, and therefore more valuable to the department. LaGuerta says he can go just to get him to stop explaining how the conference would help him. Rita is happy to see him both excited about the conference and dedicated to his job and family when he brings up that it could help him get a raise at work, thus making it easier to send Harrison to college later. She suggests that, in exchange for taking care of the kids while he's in Tampa, he can take care of them when she goes to yoga on Tuesday nights. He agrees, noting privately that it might be challenging to arrange his "activities around her downward-facing dog."
Later, in the shed, Dexter packs light for the trip, making sure to bring the hammer Arthur gave him. This is contrasted with a scene of Arthur packing the last of his sister's ashes in a small glass vial. While in Tampa, Dexter has a photo taken with Sonny Skyes, a renown meteorologist, to support his alibi.
|Road Kill - it isn't a killing on the road, it's a "Road" that leads to "Kill"ing, as Dexter plans to do with Arthur, although he doesn't. It may also refers to Arthur's "Road" of "Kill"ing as the Trinity Killer, that seems to end when he tries to commit suicide, but Dexter saves him.|
|Lila from season 2 is mentioned in this episode.|
The Moore family, including Bob Moore(dad), Nancy Moore(mom), Spencer Moore(son), and unnamed daughter, are the family that Arthur talks to in the restaurant
|"Born in blood, both of us."|
- Dexter, thinking about himself and Trinity
"Guilt, remorse, it’s what separate us from the animals.
Your conscience is eating away at you but you’re gonna feel better. Confession is good for the soul."
- Arthur ,to Dexter.
"All the more proof I don’t have a soul."
- Dexter, thinking to himself about what Arthur said
“I killed an innocent man and saved a guilty one. I won’t make that mistake again"
- Dexter, to himself
"It should have been Arthur Mitchell on my table.
Trinity, shooter of my sister. I should have…
No, no should haves – that’s not me. I just need to stop thinking about it."
- Dexter, to himself about killing innocent people
A changed man at peace with himself. Maybe only monsters feel no regret.
If erring is human, than remorse must be too. Wait – does that make me human? Huh! -
- Dexter, to himself
"This is his solution to remorse – suicide.
That’s why he could unburden himself. He knew this was next.
Will it be my only solution someday?"
- Dexter, to himself about Arthur's suicide