What a great episode of Dexter. We could watch Michael C. Hall and John Lithgow interact for hours at a time.
This week, Dexter pretended to be a guy named Kyle Butler. He showed up at Trinity's church and befriended Arthur, joining Four Walls, One Heart, the Habitat for Humanity-type charity Arthur runs in Miami.
Through building a home, Dexter got to know Arthur. Then, through Vince's DNA work, he also got to know a vital clue: Trinity has the same DNA as ashes found at the scene of the latest bludgeoning victim. Thanks to the Internet, Dexter was able to easily identity those close to Trinity that have died:
His sister (in a bathtub!); his mother (jumping off a building!); and his father (a beating!). There you have it. Trinity has been avenging their deaths at separate times for decades, even carrying around ashes of his sister and living out in the open.
Dexter takes this clue and runs with it: he tells Rita he had his apartment just for a place to store his stuff. This ieads to Dexter building a shed for himself at home and storing his killing utensils there. It's a big step for the guy.
Deb also took a big step this week, as she's sure the vacation killer didn't gun down Lundy. She's convinced it was Trinity, who she also thinks stole Lundy's files (it was Dexter actually). As if this information wasn't sobering enough for Dexter, who doesn't want anyone else tracking down Trinity, Deb also tells him that a woman she thinks was having an affair with Harry left her a voicemail.
Finally, in filler storyline no one really cares about, LaGuerta and Angel lied to the boss about their relationship being over in order to both continue working in homicide.