"The last thing I remember is Hannah," says Dexter as he wakes up stranded in the middle of nowhere. (According to his GPS, it's Kendall.) So episode seven, "Dress Code," begins.

The Hannah Dexter is fondly remembering is Hannah McKay, the one that got away. So many puns with that one line. For Dexter, she was the girl of his dreams, someone with whom he could let the plastic walls come down and just do Dexter. For Deb, she's the girl who began her downward spiral to crazy-Deb, as she rightly puts it: "The moment I asked you to kill her was the moment I started to lose myself." And for the feds, McKay is an escaped criminal, someone who literally got away.

Hannah is certainly a looker, but for Dexter, she's more than that. He can't seem to think straight with her around, and after just committing to be a "spiritual father" to a highly dangerous kid, he can't afford distractions. Thus, her presence becomes deadly for the unlikeliest person.

Zach shows up at Dexter's front door ready to start his Serial Killer 101 lessons. Dexter missed their morning meeting on account of having been poisoned the night before. Not wanting to deal with him at the moment, Dexter gives him a few tidbits of advice before sending him on his way for the day. The best piece of advice? Get a job, son. "You're a weird guy who lives with your mom, you might as well be wearing a sign," he explains. Classic Psycho reference made by a psychopath: check.

The next time Zach goes to visit Dexter at his apartment - despite having been told not to go there - things don't end quite as neatly. But that's the jaw-dropping end of the episode; we'll save the juicy bit for later.

On a lighter note, Masuka and his daughter are making progress in their relationship. Niki comes to apologize for getting mad at her new pops for giving her money, and she reassures Masuka that her after-school job is helping her pay off her debt. That much is true, at least -- there's bound to be good money in semi-stripping. Looks like Niki works at a sports bar straight out of stereotypical men's fantasies, where the waitresses serve in short skirts with their cheeks hanging out, and topless. (We're pretty sure there's not a sports bar like that near "U of M.")

Meanwhile, back at Miami Metro, Zach shows up with his lawyer and family friend, Matthews, to tell Batista about Quinn's unauthorized surveillance. Now that he's not being followed, it's time to kill, right? Right? Zach starts to sound like an overly excited puppy who wants to play with his chew toy that is out of reach. This is where spiritual father Dexter steps in: "Long before my father taught me how to do what I do, he taught me how not to do it... timing is everything." That sounds nice and all, Dex, but Harry taught you the code when you were ten, and before you ever killed someone and got a taste for killing.

Someone should tighten the leash on that puppy dog.

Instead, like a kid with a schoolboy crush, Dexter meets Hannah at her old greenhouse because he fears she might be in danger. Forget the fact that his promise to his sister was to get rid of Hannah because she was the threat; now he has to get all heroic and save the sultry ex-girlfriend. It's never a good idea returning to an ex, Dex.

At the greenhouse, we find out what Hannah has been up to. After escaping arrest, she called up an old, and rich, client of hers, Miles Castner, who always had a bit of a crush on her. Knowing that he could give her a new life, she pretended to be in love with the poor sap. Turns out, Miles is possessive, protective, and powerful. If she ever tried to leave him, he would turn her in to the police, so her only option is to kill him. She came back into town to ask Dexter for a favor, but she changed her mind because, "despite the shitty way that it all ended, you were it for me, Dexter...you're the only person that I could be that honest with."

While Dexter's love life continues to be as complicated as you'd expect for a serial killer, Debra's is starting to show some serious potential. It's no secret that Elway has it bad for her, but Deb hasn't let him get close because of her excess baggage. Elway - whose first name we learn fir the first time tonight; it's Jake - doesn't care about her past. "I just want a chance to find out," he tells her. If there's one happy ending after all this, we're keeping our fingers crossed for Deb and Jake.

When Dexter heads out to meet Zach for their 2 p.m. lesson, he gets attacked by some of Miles' thugs. Fearing that Miles might react in a similar manner with Hannah, he kill-dresses up and heads to find her. He arrives just in time to find that she has taken care of it herself. Miles was hurting her, and was about to rape her, so she defended herself. Having less work than expected, Dexter helps Hannah clean up the mess and dispose of the body. As she steps off the Slice of Life, she says, "so that's how you make people disappear," to which Dexter makes another joke: "Give or take a plastic room and a kill table." The only thing that can end their little moment is a crime scene notification.

Dexter arrives to a crime scene at his apartment complex, only to discover Cassie's apartment is the one covered in yellow tape. It's all eerily familiar to when Dexter unexpectedly found Rita in a pool of her own blood.

Zach wasn't happy about being stood up a second time, so it appears as if he left Dexter a message with his next-door neighbor. Unfortunately for Cassie, it was more of a visual message.

As he stares at his reflection in Cassie's blood, Dexter thinks, "Harry was a good teacher to me because he was normal, human, but can anything good come from putting two killers together? Whether it be student and teacher, or whatever Hannah and I have, or will it always end the same way?"

Follow Cultist on Facebook and Twitter @CultistMiami.

• Film and TV