The episode begins at the underground fight club where Lee serves as the ringside doctor. Nygma has brought Grundy use as a fighter, making him some money so that he can get his brains back. Nygma tries to convince Lee to help him get smart again but she declines.
Penguin meets with Sofia Falcone and they seem to be forming a fast friendship; he's finally starting to trust her. Jim is hiding in the next room, watching the conversation unfold. Sofia invites Penguin to lunch the next day, and he accepts before leaving. Jim finally reveals himself to Sofia and demands to know what she's trying to do. She doesn't tell him her plan, but does promise that she'll have Penguin in the palm of her hand in a matter of days.
A crooked cop is making some kind of deal with a criminal in an alley way. He hears a noise, goes to investigate, and is killed by a butcher wearing a pig's head.
Jim and Harvey investigate the murder later.. The cop's head has been covered by a pig's. Harvey tells Jim that the cop that was murdered was rumored to have been Penguin's bag man inside the GCPD. Jim goes to Penguin's club to ask if about the murder, but Cobblepot says he doesn't know anything. However, he and his lawyer do have a lead about a butcher shop robbery.
The butcher is seen in a shop, listening to opera and putting makeup on a pig's head.
Jim and Harvey follow Penguin's lead, interrogating a man who had a license to rob a butcher shop. The man said that a man called "The Professor" paid him to rob the butcher shop and drop off four heads of stolen pigs. Knowing that more victims are on the way, Jim and Harvey get to work.
Penguin is at lunch, waiting on Sofia, but Zsasz appears to tell him that she canceled at the last minute. Penguin orders Zsasz to follow Sofia so he can figure out what she's up to.
Back at the fight club, the woman who runs the ring (Cherry) introduces Grundy for his first fight. He takes a beating at first, not fighting back, until Nygma orders him to. Then, it only takes a couple of hits for Grundy to obliterate his opponent. Cherry tells Lee to take good care of Grundy because he's going to be her new champion.
Harvey and Jim go around the city talking to different cops, trying to extract info about which ones are dirty and working with Penguin. Locking one guy in the trunk of a car, they finally get the information they need. They're told that the guy they're after will be in court all day. When they arrive at the courthouse, they hear screams, and find a couple of cops dead, wearing pig heads. There is one more bag man left to find, and Jim gets a tip from a street corner musician.
Lee is patching up Grundy and she asks about all of his changes, stating that he doesn't have a heartbeat. She tries to convince Grundy that Nygma is using him, but Grundy is convinced that the two are best friends. Nygma enters to try and change Lee's mind about helping him but she still doesn't bite. Cherry comes in and mentions a deal she was with Lee, which gets Nygma's attention. He follows Lee when she leaves and discovers that she is running a clinic for people in the rough part of Gotham where the fight club is located.
Zsasz watches Sofia from his car, taking pictures of the people she is meeting with. A couple of rich men come to see her at a corner building.
Jim and Harvey figure out who the bag man is and head out to investigate the tip Jim got from the singer on the street.
Professor Pyg (the man in the pig mask), pulls up to a factory and opens up the back of his car. The cop that Jim and Harvey are looking for is inside.
Back at the ring, Grundy puts another competitor in his grave, smashing the man's head in with his own hammer. Cherry crowns him the new champion and the crowd loses their minds.
Zsasz tells Penguin what he found. Sofia had lunch with the mayor and then went to the old Gotham Heritage Hotel. She bought the old building and met with the zoning commissioner because she needed his permission to build a wall and gate around the building. Penguin loses it because it looks like Sofia has gone behind his back and is planning on overthrowing him.
Nygma approaches Lee again and blackmails her regarding her clinic deal with Cherry. It doesn't go well, since he's lost his intelligence, and Lee laughs at him as she walks away.
Harvey and Jim arrive at the factory and they find the officer sitting on a chair, alive, with a pig's head over his own. As they remove the mask, it pulls a pin out of a grenade that was in his stomach. Jim and Harvey try to run to safety and the man explodes.
Jim wakes up tied to a chair. Ahead of him is Professor Pyg, donning his terrifying mask. The villain calls Harvey a "dirty pig" and explains to Jim that he's only killing dirty cops. Pyg wants to rid Gotham of the GCPD's corruption, telling Jim that they want the same thing. He's going to butcher every single swine on Penguin's payroll. It's clear that he's a bit insane. He tells Jim that he has suffered profound loss at the hands of those in power. Just as Jim is offering to help him, Harvey can be heard screaming and Pyg runs out of the room. Jim breaks his chair and gets down to where Pyg and Harvey are. Pyg tells Harvey that he "deserves this" and slits Harvey's throat before running away. Jim tends to his partner as sirens approach outside.
Lee is helping a woman in her clinic and realizes that she doesn't have enough money to take care of all the sick people that need her help.
Penguin surprises Sofia at her house and forces her to take him to her new building. He calls her a liar and says he knows about the hotel.
Lee approaches Nygma because she needs money to make the clinic work long-term. She explains that the people she is helping are those that were affected in some way by the Tetch Virus, which she still blames herself for. The two make a deal.
Sofia takes Penguin to the building and reveals that she has opened an orphanage for the children of Gotham. Penguin and Sofia friends once again.
Harvey wakes up in his hospital bed with Jim still sitting nearby. Pyg cut Harvey's throat just deep enough to hurt him but not kill him. He wanted to make Jim choose between saving Harvey's life and chasing the villain. Harvey revealed to Jim that he's been taking money from Penguin and Jim tells him that it's over.
Professor Pyg is seen reciting a nursery rhyme while feeding a group of pigs. He ends by saying "Tomorrow, the ax shall fall."