The squad in Brooklyn Nine-Nine have had their fair share of shenanigans while working cases. They even take needed fun breaks like hosting their annual Halloween heist. But the detectives are some of New York's best when it comes to eradicating crime. Still, there's nothing wrong with a bit of comedy here and there.
Some cases were mediocre and certain events weren't 100% official police business. Throughout the show, the detectives have had some serious cases to tackle including murders, escaped convicts, and even the kidnapping of Cheddar. The detectives always managed to reign supreme, collect evidence and catch the bad guy, especially when it was a serious situation.
White Whale (Season 5, Episode 21)
While Terry helps Jake get wedding planning done, Rosa and Amy work on a serious case. The bane of Rosa's existence resurfaces after seven years in hiding. Sergio Mindar is a ruthless killer who built his own meth empire. Rosa and Amy were in charge of the case but were never able to catch him.
The case is so important that Amy leaves the wedding duties to Jake on his day off. After being foiled once, Rosa and Amy go undercover at a nursing home to interrogate the suspect's mother. After no leads, they soon realize that Mindar stashed his money at the nursing home and had an accomplice. Amy and Rosa finally catch their guy.
Undercover (Season 2, Episode 1)
At the beginning of season two, Jake is deep undercover in an Italian mob. His cover is as an ex-cop who switches sides to a life of crime. At the wedding for two members, Jack gives the signal for the precinct to swarm in without blowing his cover. Despite the sting being successful, one mobster got away.
This leads Jake having to go undercover once again to get more information. He plays off that he was never arrested in the takedown. His information leads him to question the mobster's girlfriend. After a brief showdown involving a gun to Jake's head, Jake finally gets what he needs. Sadly, Jake gets there too late and the mobster escapes.
The Puzzle Master (Season 5, Episode 15)
Jake and Amy take on a mildly serious case that has Jake feeling jealousy. Jake rewards Amy on passing the Sergeants exam with her last case: a serial arsonist connected to the Saturday crossword puzzle. To make things even more exciting, they are connected to Melvin Stermley, Amy's favorite puzzle master.
Fans know that the guest star portraying the puzzle master happens to be Melissa Fumero's real-life husband, David Fumero. As the three try to find new evidence and solve the case, Jake gets jealous at how much Amy and Vin have in common. Using puzzle clues and detective work, they solve the case.
The Pontiac Bandit Returns (Season 2, Episode 10)
When it comes to side characters in the Nine-Nine, Doug Judy is a fan favorite. In season two, he's back in custody but offers some juicy information to get a plea deal. Jake and Rosa are against the idea entirely after Judy has evaded their arrests many times.
In the need, Holt assigns Jake and Rosa a new case to catch a notorious drug dealer called, "Giggle Pig." With the help of Judy, they get some valuable intel and set up a sting operation. The sting is successful but Judy once again escapes.
Debbie (Season 7, Episode 5)
The squad takes a huge hit in this episode. They're in shambles as someone has stolen twenty bricks of cocaine and two machine guns from evidence lockup. The new officer, Debbie doesn't do a good job at hiding her involvement. The squad tries to arrest her and question her for information.
She refuses and Jake and Rosa come up with a plan. They break Debbie out and pretend to be on her side, all to get information on the real suspect, Silvio Nucci. They take her to a motel but Debbie ends up doing too much cocaine and aiming firearms at Rosa and Jake. Jake uses Debbie's crush on him to calm her and pretends to double-cross Rosa. At the pickup, Jake and Rosa arrest Nucci.
Maximum Security (Season 3, Episode 21)
This episode of Brooklyn Nine-Nine is one of the best when it comes to going deep undercover. The squad gets ready to gather information about Figgis and his FBI informant. As part of their plan, they send Rosa to a women's maximum-security prison but an inmate spots Rosa, ruining her cover.
Instead, Amy takes the lead. Jake and Boyle pose as her OBGYN doctors but Jake worries for her safety and almost risks her cover. Amy gets respect from the inmates when she punches Jake to the ground and is invited to join the gang of Figgis's sister.
The Slaughterhouse (Season 4, Episode 20)
The biggest shock to fans is when Jake and Rosa are double-crossed and framed by Melanie Hawkins. Both Jake and Rosa see Hawkins as their idol. They were tracking a bank robber and his men to a warehouse but their suspects escape. Rosa and Jake learn that some of the henchmen are undercover officers working for Hawkins.
Jake overhears Hawkins talking to the suspect and learns they're working together. In the next episode, Jake and Rosa ask for help from Pimento due to a lack of evidence. They pretend to be on Hawkins' side and even get drunk with her. The following day, they take part in a bank robbery hoping to arrest Hawkins to only be framed by her instead.
Greg And Larry (Season 3, Episode 23)
Episode 23 is a continuation of episode 22 in season three. While looking for information on Figgis, the squad comes to a dead end so Holt calls in his FBI friend to help. As the case goes on, Bob and the squad hatch a plan to break into the FBI to get a file to build a case against a suspect.
In a turn of events, the squad realizes the FBI informant to be Bob and that Holt is in danger. After sequestering Bob, they try to move him to Rosa's apartment while evading Figgis's henchmen. They interrogate Bob on the location of the FBI file that could take done Figgis. After they are successful in their case, Jake gets a message from Figgis promising to kill him and Holt; forcing them into witness protection.
Sicko (Season 6, Episode 17)
Three young men, all murdered in different ways, but mostly disfigured. The killer also opened their bodies and ripped their hearts out. The case is a serious one and Jake and Boyle are on it. The Commissioner pressures them that if they don't solve the case, there will be consequences.
To get some information, Jake and Boyle visit his old cannibal cellmate. Holt is displeased when Jake and Boyle use the Commissioner's tipline app. They get the suspect but learn that the tips came from the Commissioner's assistant. They were using the app to hide their illegal wiretapping.
He Said, She Said (Season 6, Episode 8)
Between all the laughs and comical scenarios, Jake and Amy take on a serious case involving a sexual assault. This isn't the first episode where the show addresses major social issues. This case hits home for Amy as she too experienced sexual misconduct before transferring to the Nine-Nine.
An investment banker is admitted to the hospital with his male anatomy broken after being hit with a car by his female coworker who claims he tried to sexually assault her. Amy takes the case seriously and wants to bring the assailant to justice even if it means jeopardizing the victim's career.