- "Your father's blood really does flow through your veins. Luckily, not for long."
- —Oswald Cobblepot to Sofia Falcone
Gordon and Bullock are hot on a serial killer who has been assassinating cops and dressing his victims in the severed heads of pigs as his signature mark. Meanwhile, Sofia tries to win over Penguin, and Thompkins, Nygma and Grundy find themselves an unlikely home at Cherry's place.
At the fight club, Edward Nygma talks with Lee Thompkins for help in order to fix his identity crisis but she angrily refuses to help him following his previous actions. Oswald Cobblepot and Sofia Falcone meet in order to fully acknowledge each other's partnership. In another part of the city, a police officer investigates a gunshot. While searching the area, he is butchered by a man wearing a pig mask.
Jim and Harvey investigate the murder, finding the killer put a pig's head on the officer's head. The officer also was a bagman on Cobblepot's payroll. After interrogating Cobblepot, Gordon gets a clue from a man, Wally Clarke, who applied for a license, discovering a headless pig in his apartment. Wally states that he just retrieved the pigs from a butchery and left it for a man known as the "Professor". Cobblepot meets for dinner with Sofia but when she fails to show up, he has Victor Zsasz to follow her. In the fight club, Grundy manages to beat another fighter for money, much to Nygma's delight. Nygma then finds out that Lee is leading a clinic in her apartment to help people.
Gordon and Bullock get a clue from an informant about dirty cops that may be affiliated to the Professor. They find them dead on a bench with their pig masks on but get a lead that a white van left the bodies. Another officer is also kidnapped by the Professor. They follow to a warehouse where they find the officer. However, he has a grenade in his stomach, killing him and knocking Gordon and Bullock out. Gordon wakes up tied to a chair where he is confronted by the Professor. The Professor states that he was once a cop but decided to end the corruption by killing any corrupted officer. The Professor leaves to kill Bullock in another room. Gordon manages to free himself, but the Professor cuts Bullock's throat and escapes.
Cobblepot is told by Zsasz that Sofia seemingly bought an abandoned hospital and was seen meeting with many businessmen. However, she shows him that in fact, she has opened an orphanage and is forgiven for his misstep. Lee, after finding her medicine is running out in the clinic, decides to accept Nygma's money and help him with his identity crisis. She also states that she's only remaining in Gotham because she feels responsible for the Tetch virus. Bullock wakes up and is confronted by Gordon, who tells him he knows that he has been on Cobblepot's payroll. Bullock finally admits he has been on his payroll since the licenses began, saying his debts were the main reasons. Gordon tells him it will stop. The Professor, now dubbed by media as "Professor Pyg", is seen taking care of pigs in an undisclosed area.
- The surname of Professor Pyg's first victim, Metzger, is the German word for butcher.
- The title gives a nod to the 1975 film, "Dog Day Afternoon".