It's Deb's first official day back at work, and they're investigating the murder of a young Nicaraguan woman. The twist is that they were tipped off to the homicide after discovering her arm in the belly of an alligator. Turns out the main suspect is a twisted fashion photographer who might have a violent past. After sexually harassing Deb, he jumps to the top of the list of Dexter's next victims.
Dexter and Trinity have some man time, going out into the woods at 6:30 AM. When Trinity offers Dex his choice of weapons - chainsaw, ax, saw, or pickax, Dexter is convinced that only one of them will make it out of the encounter alive. But surprise! They're just going to cut down a tree together. Whew. After Dexter successfully starts the chainsaw when Trinity tries and tries but can't do it, Trinity gets unnecessarily snippy and weird.
On the way back into the city, Trinity accidentally hits a deer on the road. Dexter insists that Trinity put it out of its misery, but he refuses, getting sick and nervous at the thought of killing the deer. So, Dexter takes the ax, and kills the deer. I believe what we're supposed to gather from this scene that, unlike Dexter, Trinity's killing stem from an altered psychological state, not a constant way of hardness and insensitivity, like Dexter. Does this make him better or worse? Will it help or harm Dexter's efforts to both learn from the most successfully serial killer in recent history, or harm them? We'll see!
Dex investigates the creepy fashion photographer, and of course, it turns out he's killed a bunch of beautiful South and Central American girls who were in the US illegally. Bring on the killing!
Dexter tries to go over the photographer by ambushing him outside a swanky club, but freaking Quinn is there too! Turns out Quinn has a bug up his butt about Dexter ever since he found that Dexter knows Quinn stole money from a crime scene. Quinn is also pressuring Deb to sit for an interview with his reporter girlfriend, something that Dex is adamantly opposed to. Quinn seems to think that Dexter has secrets, so is trying to figure them out to have something to match Dexter's knowledge about him. Oh Quinn, this is not a road you don't want to go down. Don't you remember Sergeant Doakes? You don't want to end up fried in a cabin, and that's where you're headed if you don't back it down.
So, Dexter has to delay the killing and instead, take Cody on an overnight boating trip with the Young Sailor's Club (adorable!). They tell scary stories around the fire, and despite protestations that he doesn't know any scary stories (yeah, right), Dexter starts telling the story of the Trinity killer, before he's interrupted by a fellow chaperone and all the kids go to bed. BUT, after everyone is tucked in night and snug, Dexter sneaks to the photographer's in a second attempt to kill him. This time: success! Although the photographer makes the requisite pleas of innocence, Dexter knows better, and takes care of him.
PLOT TWIST - after getting to the station, we see that the photographer's assistant has been taken in for the murder of the girls. It turns out they have DNA evidence, security camera footage, the works. Ruh-roh. Looks like Dex just killed an innocent man! This is certainly a new situation for our hero - what will he do? How will he handle such a blow to his method?