Dr. Roma Maffia presses Dexter to tell Rita why he really kept his apartment. Here's where things get a lil' bullshitty. "Because...I need...space?" Dexter says. "To keep...my stuff?" Technically true, but he's also searching for something that will sound honest more than actually is honest. Hilariously, Dr. Roma Maffia interjects that Dexter means he needs space for himself within the marriage, and Dexter is like, "Yeah, that too, but speaking literally, I have shit that needs a place to get set down." At this point, Rita's so pleased with the honesty (or the illusion of honesty) that she's more than willing to give Dexter all the space he needs. Dr. Roma Maffia seems to view this as an unqualified success!
Back at the Mitchell household, Sally is taking a bath in what appears to be skim milk, when Arthur sneaks into the bathroom. The soundtrack plays it as very sinister, but it's actually just a husband wanting to join his wife in the tub. Sally remarks that he's always doing this, though she clearly doesn't mind. He steps in (bringing Naked Lithgow triumphantly back into our lives), and as he arranges himself behind her, it becomes incredibly apparent that this tableau is identical to the scene he sets for his bathtub killings. As is the case with the best Trinity/Arthur scenes, it's deeply, deeply creepy. He even grabs a hand mirror so he and Sally can look at each other in their bliss. Sally, I should mention, is played by uber-character-actress Julia Campbell, who you've seen at least once provided you've watched any television show in the last decade. Off the top of my head, she played the teenage gymnast's mom in the first season of In Treatment, though the role I most remember her for is Jerry's girlfriend in the "Frogger" episode of Seinfeld. Anyway, check out her IMDb page sometime. It's a clinic in how an actress can stay remarkably employed and yet incredibly anonymous.
The water in the Mitchell's tub dissolves into the milk carton in Dexter's kitchen, which grosses me out to no small degree. Dex is pouring himself a coffee when he's joined by Deb, who looks remarkably less like a 10-car pileup. It's because she has renewed purpose: Nikki Wald didn't kill Lundy, Trinity did. She's basing this off of her assumption that Trinity stole Lundy's research, so she's right (or so we're all assuming) for being wrong. Either way, Deb's psyched that she can track the cocksucker down herself; she doesn't have to feel helpless anymore. DVO is annoyed that he now has to plan Trinity's death and worry about Deb getting too close. But it seems like he's taking the path of least resistance for now. Deb says she's not taking the case to LaGuerta yet. She wants to make sure first, "don't want to step on my dick." (Aw, Deb, you ARE back on track!)