Cut to El Deano, who's trying to bash his way back into Sam's area when the girl attacks him -- Gordon turned her, as you probably inferred. I assume he did that much earlier to give her time for the change to take, but I won't dwell on it either way, because after getting tossed to the floor, Dean draws the Colt and shoots the girl right in the head, which, with a flourish of electrical energy, kills her dead.

Back in the Land Of Infrared Speechifying, Gordon says that Sam has a lot of people fooled, but he knows better. He goes on that Sam's got something evil inside of him, and he should do the right thing and kill himself, which is what he intends to do once his final mission is complete. It'd be a pretty cool trick to see him pull his own head off. Finally, he charges Sam...

...and tackles him through a wall right into the area where El Deano is currently chilling. Dean tries to get a shot off from the Colt, but Gordon's too quick for him, getting him up against the wall and biting his neck. This is enough to snap Sammy out of his daze, and he comes at Gordon, who punches him in the stomach and then boots him in the face, which is no surprise, because I may be new around here, but I'm not so new that I don't know that Sam suh-uh-uuucks at the hand-to-hand. Or at least he does when he's bare-handed, but apparently it's a different story when he has a moment to accessorize. Because in the process of getting his face bashed in, Sammy manages to pick up a cord of razor wire, which he sticks into Gordon's throat. Gordon hisses and bares his teeth, but the Super-Steely Puppy-Dog Eyes crank up to eleven, and with a delightful amount of spurting blood, Sammy pushes the wire all the way through Gordon's neck, spectacularly decapitating him. At that moment, from somewhere a couple states over, I distinctly heard what sounded like a vaguely reptilian voice gleefully shouting "GOOOOOOOOOOOORE!" And all I can say to that is: Indeed. That was effing genius. Sammy takes a look at Gordon's newly-liberated head, tosses the wire to the floor, and looks ill as Dean gets unsteadily to his feet. Apparently he missed the whole thing, which sucks not a little for him, but as he takes in the tableau and casts an appraising eye at Sammy, his brother just raises his eyebrow like, "Well, that was a thing, huh?" Heh. The boys start to limp away, and Dean, holding his neck wound, points out that Sammy charged a vamped-out Gordon with no weapon. "That's a little reckless, don't you think?" I don't know -- does "reckless" mean "AWESOME"? I'd have to say yes, given the editorial appearance of the METAL TEETH CHOMP!