The random bits and pieces first: Nikki forgives Masuka for his bumbling last episode, but when he realizes she's working at a topless bar to service her debts, Masuka offers her part-time work in his department. Elway catches Deb checking into Hannah and then tells her off for, essentially, spurning him. Later, Deb assures him that he doesn't want to be involved with her, but does thank him for being the reason she's survived her recent troubles. She even starts calling him by his first name! Jamie wants to move in with Quinn, who's a typical slackjawed guy about it at first, but when Zack comes into the station with his lawyer to formally request Quinn cease his constant surveillance and Batista goes along, Quinn tells him he and Jamie are moving in together just to spite him. Healthy!
Dexter comes to in a remote location, having also apparently been drugged by Hannah. He's relieved to learn that Hannah left Deb unharmed, but Deb understandably feels like her life is just about complicated enough without Hannah's return, so she tells Dexter to get her gone one way or another. Via his access to traffic footage, Dexter tracks Hannah through her car rental to a marina, at which he discovers that she's apparently got a new beau rich enough to afford a rather large yacht. It's pretty obvious he's jealous, so even though it's clearly a terrible idea, Dexter enlists Zack to help him get into a rich-people-only club at which Hannah and her guy are spending the evening. Catching her temporarily alone, he learns that she's changed her name to Maggie and is married to the dude. Speaking of which, it turns out international-casino-mogul "Miles" knows all about Dexter, too, although the version he's heard from his wife might be slightly slanted.
Deb realizes that Dexter still turns into a confused horny teen when Hannah is on his mind, so she goes to Vogel for advice, but Vogel soberly cautions her to consider all the consequences before taking matters into her own hands. Meanwhile, Miles threateningly confronts Dexter, after which Hannah agrees to meet him. She bitterly tells him she needed someone of Miles' means after Dexter betrayed her, and while she revealed herself to Dexter in the hopes that he would kill Miles for her, as he's horribly controlling and possessive, she realized that she still loves Dexter, and as such she doesn't want to risk him like this.
Deb puts a tracker on Dexter's car, and in the parking lot she runs into Cassie, who confesses she's still kind of hung up on Dexter, and Deb's like, maybe you want to rethink that? Miles sends goons to beat Dexter up, and later, on the boat, Miles physically assaults Hannah as he tells her that they're leaving that night and he's never letting her out of his sight again – unaware that Dexter has arrived at the marina. He sneaks onto the boat – and discovers that Hannah's killed her husband, although in a bloodier way that usual for her. He helps her clean the place and get rid of the body – while Deb watches the whole thing from her car.
Zack shows up at Dexter's, as Dexter's unscheduled Hannah-induced nap caused him to miss an appointment, and Cassie and her new man see them in passing. Dexter tells Zack that he needs to get a job to serve as a cover life, but Zack's obviously antsy to kill again. Unfortunately, Dexter has to blow Zack off once more due to all the Hannah-related stuff going on, resulting in Zack angrily pounding on Dexter's door with Cassie seeing him again. In the end, Dexter gets called to a crime scene in his apartment building – Cassie's been bludgeoned to death in a similar way to Norma Rivera. Did Zack do it? (I think it's the boring boyfriend, but Dexter isn't so sure.)
So it wasn't completely clear to me last time from the difference in their apparent energy levels, but it seems Hannah drugged Dexter as well as Deb, as Dexter is awakened on a riverbank someplace by his phone. It's Vogel, who wonders where he's been all morning, and as the full significance of what's happened hits, Dexter tells Vogel he can't really talk, but Vogel presses on to inform him that Zack called. "I'm so glad you decided not to kill him." Look, I'm not going to make a federal case out of it each time someone on this show who should know better acts like cell phones are secure modes of communication, but that's only because I'm not getting paid by the word. But give me a fucking break here, Vogel. Whether he's feeling the same way or not, Dexter drops Vogel to switch over to a call from Deb, who's also groggy but conscious as she asks where he is. A wider shot shows he's by some industrial plant in, as he tells Deb thanks to his GPS, Kendall, and he cuts through her confused questions by telling her to pick him up and assuring her they'll talk when she gets there WHAT A GOOD IDEA.
Cut to DVO wondering what Hannah wants, given that she didn't kill either of them, when Deb comes driving up and is like, my mind cleared up enough on the way over to figure out it was Hannah, right? Dexter confirms that and wonders what Hannah's next move might be, and Deb points out that if they were normal law-abiding citizens, they'd go to the Marshals. It's been a long time since he was in Miami, but that still makes me reflexively hope for a Raylan Givens appearance. Dexter tells Deb Hannah knows too much about him, and when Deb points out she didn't spill her knowledge when she was arrested last time, Dexter counters that Hannah was in love with him then. "Drugging me and leaving me on the side of the road might suggest that's changed." If you think that, Dexter, you need to watch more reality television.
Dexter realizes that the street they're on is lined with surveillance cameras, so he should be able to get hold of the footage using his PD credentials and track Hannah down. Deb takes a long moment before telling Dexter that the moment she asked Dexter to kill Hannah was the moment she started to lose herself, and now that she's just getting her life back, she's feeling ill-equipped to deal with this. "I want her gone." Presumably, given what she just said, she means "gone" to a place on Earth, not below. Dexter assures Deb he'll take care of it…