In terms of "things I'd never willingly watch unless I had to," the beginning of this episode is right up there. Two guys are following a GPS signal to a house to try and find their dog via his GPS collar. They hear barking from inside and flag down some cops, one of whom realizes they might want to go inside. They barge in and find a ton of men around a ring watching a dog fight, and heartbreakingly one of the men yells, "Nathan!" and runs to his dog -- or rather, what's left of his dog, lying in a puddle of blood on the floor. Excuse me while I go cry, or vomit, or both. Later, Green and Lupo are called to the dog morgue where they look upon the mutilated bodies of one of the fighting dogs as well as Nathan, who was used as bait to get the dogs riled up before the fight. And...now I have to go vomit again. It turns out they were called because the doc found a human finger inside the stomach of the dead fighting dog. This is going to be an awesome hour of TV, boy howdy.
The boys head up the courthouse steps where there's a crowd of rowdy protesters and their dogs chanting against the eight men who have just been arraigned for dog fighting. Green comments on the fact that they don't get these crowds for people who kill humans. Yes, it makes no sense, but I'm right there with them. They walk up to the guys and ask to see their fingers, which turn out to be all accounted for. Then they're accosted by a reporter, played by Lara Flynn Boyle, so we know for sure she'll be important later. They brush her off and head off to go see their own doc, who hands them the finger, which still had some nail polish on it and was pinpointed as belonging to a victim in (probably her) early thirties or younger, who was recently dead. There was some sort of chemical burn on the skin, and the finger was in the dog somewhere between four and eighteen hours.
The boys walk in on a meeting between the eight and their lawyers to let them know the detail about the finger, but don't get much out of them. Green assures them he doesn't care about the dog fighting case but that cops are searching the house now for other body parts. The owner of the house, Carlin, tells them where the kennel is that the dogs came from, and while he does the camera zooms in on a guilty-looking dark-haired guy fidgeting in his seat. They go out to the country somewhere with the actual dog owner, Mr. Mackey, in tow and meet another detective, Cabrera. Mackey is showing them the house to try and convince them he didn't feed them any body parts before he shipped the dogs to the city. Some cadets are apparently straining all the dog droppings and have come up with a pile of bones that Mackey insists are from cats. Is that the point where you think about a possible career redirection? There's a lot of description I won't repeat about the conditions in which the dogs were kept -- the pertinent info is just that he insists he didn't run the show himself and begs them to make a deal with him.