Halloween is the first Halloween episode of Brooklyn Nine-Nine.
Amy complains about Halloween being the worst. "Everyone's drunk, wearing a mask and carrying a fake gun." Charles walks in wearing a costume. The squad tries to guess what he is, making fun of him along the way. Charles says he's obviously Mario Batali, a celebrity chef.
Later at the briefing room, Holt informs them that they need 2 undercovers at the Dekalb Street Warehouse Party. He decides to send Boyle and Santiago, much to Santiago's disappointment.
Jake starts complaining about how these perps are so stupid and how he would make a better criminal than any of them. Holt is certain that he would be caught, prompting Jake to issue a challenge: Steal Holt's Medal of Valor before midnight. If Peralta loses, he will work the next five weekends, no overtime. He also won't tell about the time he saw Holt wearing short-shorts outside of work. If Holt loses, he has to do all of Jake's paperwork and publicly state that Jake Peralta is an amazing detective/genius.
Peralta is at Gina's desk. He says the two of them never talk anymore and he asks about the captains schedule for the day. Gina says she won't help him rob Holt, but finally gives in and informs him he has a meeting downstairs in 10 minutes.
Meanwhile Amy and Charles are standing outside. Amy has a skeleton costume on, which smells like vomit because the department never washes the costumes. She tells someone dressed as Raggedy Ann no-open containers, to which she realizes they are cops.
Holt hears Peralta above his ceiling. Before his meeting, he takes his Medal of Valor off the wall and into a locked safe is a locked cabinet with the key on him. Jake falls from the ceiling. After, Charles and Amy come back to the precinct after being egged. Terry says the bet's not about him or it's about how smart he is, it's about Captain Holt. After Holt's meeting, he sees Peralta dressed as a janitor snooping around in his office.
At the party, Charles is having fun and blending in, while Amy is still complaining about Halloween. They notice a partier with drugs.
Holt is on the phone. He is told that the soonest his office can be fixed is Monday. Suddenly, feathers fall through the vents. Holt steps outside, only to see Peralta holding pigeons.
Amy had paid Hitchcock 50 bucks to trade places with her. That is revealed when Boyle talks about a guy who walked in full astronaut costume, who gave him a high-five, to which Hitchcock accidentally responds.
Jake calls the captain out of his office with the royal babies. They steal his keys. Later, Amy runs into Holt's office saying some officers just arrested Peralta for scaling the side of a building with a blow-torch.
5 minutes until the deadline, Holt is questioning how smart Jake is. Jake then tells him a story. After he fell through the ceiling, he had the idea of Herman, the janitor. When Jake was called out of Holt's office, he didn't catch Rosa, who was picking the lock to the cabinet. Peralta managed to create a diversion so she could escape. After, Holt was so focused on getting his keys back, he didn't notice Terry stealing his phone. Charles swept the phone for the 4 numbers Holt types the most, the four in his passcode. Peralta assumes that he uses the same 4 numbers for the safe as well. While Peralta is telling the story, Charles stuffed himself though the window and tried many combinations which could take 5 minutes. After the deadline, Holt opens the door, and Charles is holding the Medal of Valor.
Amy admits that she acted as a jerk, and decided to celebrate Halloween with Boyle, and Holt announced that Jake Peralta is an amazing detective/genius.