'Dexter': Dark passenger disembarks

You won't hear any more whispery voiceovers from Dexter (Michael C. Hall) about his dark passenger. In last night's episode, "The Dark … Whatever," insight from his serial-killer girlfriend, Hannah McKay (Yvonne Strahovski), leads to the realization that Dexter kills because he wants to, not because he is forced to by some evil dude living inside his head.

"It turns out, I’m no puppet," Dexter says. And even ghost dad concurs. ("I gave you the code," he pops in to add. "The dark passenger was all yours.")

In exchange for this insight, Dexter lays the L-word on Hannah, although he prefaces his statement with "I think…," which is not typically a woman's dream way to hear it.

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Dexter's newfound personal responsibility kick makes it easier to kill Hannah's father, Clint McKay (Jim Beaver). He doesn't live up to Dexter's code but passes the total jerk code with two jerks to spare. This convicted felon shows up asking Hannah for $20,000 to start a crawfish farm (code for paying off a gambling debt). After she initially refuses, he blackmails Dexter for the same amount, threatening to go public with some information from Hannah's childhood that could land her in jail.

Because he exists solely as a prop to demonstrate Dexter's emotional breakthrough, we hardly meet Clint before he's taped up to Dexter's boat deck. ("You got the devil inside you, boy," he says. "No, I think it’s just me," Dexter replies.)

In other plot developments, Dexter's lizard brain was wrong about the identity of the Phantom, the serial arsonist who has left seven extra-crispy corpses in his wake in the last two weeks. It's not Philip Bosso (Brett Rickaby), the Fire Marshall Bill look-alike who lectures Metro on how to investigate arson. That dude's just a weirdo.

The Phantom is really a psychotic named Joseph Jensen (Mike Foy). A janitor at the site of the first blaze, Jensen was recently released from a mental institution after serving a long sentence for an arson committed not by him, so he claims, but by an old friend named "Bobby" (the name scrawled at every arson site so far). Jensen was already questioned and released by Batista (David Zayas). But Dexter tracks him down via a fingerprint he left with an ungloved hand on the railing of a bus we watch him torch in a fireproof suit -- along with several of its passengers.

Something stops Dexter in the middle of serial-killing Jensen in his own basement, however. And it's not clear what it is. Is it his conscience for promising Deb (Jennifer Carpenter) never to steal any investigations away from her? More likely, he simply hears Metro approaching to arrest Jensen. Either way, Jensen is left alive and that can't be a good thing for Dexter.

Actually, lots of not good things for Dexter seem to develop simultaneously. LaGuerta (Lauren Velez) and Tom Matthews (Geoff Pierson), the bitter former enemies and tenuous current allies, meet to discuss LaGuerta's prime suspect. Tom says investigating Dexter Morgan is a waste of time. Nevertheless, he agrees to accompany her to the Everglades cabin, where Doax's bloody last stand occurred.

The cabin is long gone, but the landlord says he rented it to a Santos Jimenez. This was one of the three people responsible for murdering Dexter's biological mother after discovering that she was a confidential drug informant. The truths Matthews knows about the Morgan family then pour out as freely as the alcohol he and LaGuerta share at a bar: Dexter’s brother was the Ice Truck Killer. And Dexter watched his mother get stabbed and chopped up -- a la the Bay Harbor Butcher -- in front of his young and impressionable eyes.

Tom volunteers to question Dexter.

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Meantime, Dexter's co-workers hear that he's dating Hannah. Batista warns Dexter to be careful; Masuka (C.S. Lee) high-fives him because Hannah is so hot. Deb worries how Dexter intends to maintain his low profile in spite of this revelation. And she warns him: "I’m not going to let that woman get away with murder. I have compromised the (expletive) out of myself for you. I am sure as (expletive) not going to do it for Hannah McKay."

Deb then pops a pill and we are shown a close-up of the Xanax label. (Close-ups like this usually mean that rehab is not an incredibly distant number of episodes away.)

George (Jason Gedrick) calls Quinn (Desmond Harrington) to let him know that he's sending Nadia (Katia Winter) off to a Dubai sex club and there's nothing he can do about it. Quinn shows up with his gun drawn, intent on proving otherwise.

"What are you gonna do, Mr. Policeman," George teases. "You’re gonna shoot me in my own club?"

So Quinn does. Then he quickly tries to cover up the murder by handing George's gun to Nadia and asking her to shoot Quinn in the arm, to help him feign self-defense. When Batista shows up, Quinn asks him not to mention that Nadia was a witness, since she will be killed by the Koshkas and she's here illegally anyway. Batista goes along with the lie, and he knows the even deeper one: There was too long of a lag between the first and second shots for Quinn's story to be true.

Finally, it turns out that Dexter was a little too late doing his thing to Clint McKay. Hannah's dad had already phoned Deb, leaving the incriminating info about Hannah: the identity of a former roommate, Arlene Schram,  who witnessed her rat-poison a counselor when she got out of juvenile hall.

"Dexter" airs Sunday nights at 9 p.m. ET/PT on Showtime.