Dexter blames himself for Vogel's death even as he removes all evidence of his presence in Vogel's life, and Deb, pretty moved herself, vows to use her return to the force to help Dexter, although she warns him that if she catches Daniel she won't be handing him over for the table treatment. Also, Hannah's booked an itinerary for her, Dexter, and Harrison for only two days hence, but Dexter wants to take care of Daniel first, and an even bigger problem time-wise is the approach of a tropical storm that threatens to ground any outgoing flights.
From here, Dexter gets the shock of his life when he gets called into an interrogation room in which Quinn is interrogating Daniel on the Cassie case. Daniel claims just to want to clear his name, so he submits to a DNA test, which gives MM the knowledge that Daniel was Vogel's son. Also, Dexter puts two and two together and checks out the abandoned hospital at which Daniel's been killing his victims; in it, he finds Daniel's laptop with video of all his kills on it. Meanwhile, Clayton asks Deb about the hospital incident, and Deb tells him she was the one who took Harrison in. Not believing her, Clayton goes to Elway and tells him his suspicions, so Elway stops by to give Deb a fake apology while checking out the place, and although Deb kicks him out quickly, it's clear that Elway is on to Hannah, so Deb gets her to an airport hotel to wait until it's time to go.
Dexter lists his place, and who should show up to make an offer but Daniel, who proposes that he and Dexter take their leave of each other and both stay alive, adding that Dexter has much, much more to lose than he does – he'll go after Dexter's family if he doesn't relent. Dexter fakes his agreement but still plans to take Daniel out despite the mounting pressure on him to get out of Miami, and he sends the videos of Daniel's Brain Surgeon kills to a news outlet; with the combination of that and the arrest warrant MM has put out on Daniel thanks to the DNA test showing his familial link to Vogel, Dexter figures Daniel will be returning to his door, which does in fact come to pass – but Deb helps Dexter captures him, and soon, Daniel's waking up in the very chair in which he killed all those people. Dexter realizes that the kill holds no joy for him anymore, so he changes the plan up and has Deb come arrest Daniel – unaware that Clayton has been tailing Deb. When Deb steps out to say goodbye to Dexter, Clayton bungles his way in and releases Daniel, who kills him and uses his gun to shoot Deb, although she does land one in his arm before he escapes. With Deb's life hanging in the balance and Elway at the airport just steps away from Hannah, it looks like the storm's not the only dark thing coming in the series finale.
As Dexter uses Vogel's porcelain sink to rid himself of the blood on his hands, DVO vaguely blames himself for her death before going on that he's going to have to remove himself from her life. This leads to a quick sequence of him snagging some of her tapes and records before going to her computer and copying and deleting a bunch of files that presumably mention him. (You'd think that someone with the computer skills that Dexter has shown would have an idea more sufficient than this. Has he never heard of Time Machine?) DVO then says he has to call this in because he can't risk being spotted as he leaves the crime scene. He then kneels over Vogel's corpse as DVO offers some thoughts about avenging her death.
When then smash-cut to later where we find a bunch of MM personnel milling about the scene. Batista is sitting with Dexter (is this the first time a lawman has seen him in his signature I'm Going To Kill You brown shirt?) as he ascertains that Dexter (and Deb) were friendly with Vogel. Dexter's story is that she called him and asked him to stop by (well, that at least will match the phone records), but when he got there, he found the door kicked in and ran into the house, where he tried to stop her bleeding, but she was already dead. Quinn pipes up that "Miller" (she hasn't been around in ages, so not sure why we're pretending here) heard from a neighbor who said they saw a white male "in his forties" fleeing the scene in a pickup.
As long as we're truth-telling here: Daniel does not look anywhere near his forties, nor is Darri Ingolfsson even thirty-five. Also, it's nice that no one saw Dexter enter Vogel's place, or they would have reported that he was the one who kicked the door in. Batista sends Dexter home (probably much to his chagrin since he won't have the opportunity to cover up anything he missed), but they agree they'll see each other the next day for Dexter's farewell to the job. As Dexter heads out, DVO intones that Daniel may have a head start on him, but he intends to catch up. That self-confidence will probably serve you well, Dexter, even if I don't have the slightest idea where it's coming from.
Quite early in the morning, Dexter turns up at Deb's and gives her the bad news. They commiserate about the loss, agreeing that without Vogel, they might not have found their way back to each other. It's a nice sentiment, but I think they should at least give the fisherman who foiled Deb's murder-suicide attempt an assist. Dexter looks as moved as he gets before he seethes that with Daniel out there, Harrison needs to be safe with Jamie at Batista's place. Deb offers to go back to work that day so she can aid Dexter in his search for Daniel. Dexter's wary of the position Deb will be putting herself in, but she cautions him that should she find Daniel first, he won't be appearing on Dexter's table. Dexter gives Deb a processing side-eye, but any further discussion is curtailed by Harrison appearing with Hannah and proudly announcing that he combed his hair. Hannah's dry addition that "He insisted" probably tells you all you need to know about the results.