A ensemble comedy following the lives of an eclectic group of detectives in a New York precinct, including one slacker who is forced to shape up when he gets a new boss.
After Holt is transferred to the NYPD Department of Public Relations, the new captain's arrival causes the precinct to dissolve into chaos, despite Terry's best efforts to keep everyone on point. Meanwhile, Jake and Amy face the aftermath of their "for reals" kiss.
The Nine-Nine gets another personnel change that could put Jake and Amy’s budding relationship at risk. Meanwhile, Terry assists Holt with an important public relations matter, and Rosa and Gina try to convince Charles to rethink his affection for a fellow officer.
Jake thinks Boyle might have met his soulmate in Genevieve, an art gallery owner, and he tries to help set them up. Meanwhile, Rosa deals with inter-precinct theft and Holt seeks Amy’s help with an image campaign.
When investigating a serial killer, Jake enlists Holt’s help in an attempt to solve the case off the radar. At the precinct, Rosa and Amy are forced to deal with demands from an old adversary and Terry discovers a new obsession.
The third installment of Captain Holt and Jake’s Halloween heist culminates with a tie-breaking competition to claim the title of “amazing detective slash genius.” This year, Jake and Holt split the squad into two teams to help them win.
Jake and Charles convince Terry to take a weekend camping trip as a much needed "babymoon," but they soon realize it might not be the idealistic weekend for which they had hoped. Meanwhile back at the precinct, Holt gives Rosa some important relationship advice and Amy enlists Gina's help to prepare her for an important presentation.
Jake and Amy convince the Captain to let them work a case together involving a new street drug, but their new relationship gets in the way. Meanwhile, at the precinct, Charles panics when he realizes he’s damaged one of Holt’s prized possessions and Terry teaches Rosa a lesson in discipline.
Terry leaves Jake in charge of entertaining his pregnant wife, Sharon, while he and Rosa head to Rikers to learn more about the Douglass Street murders. But when Sharon's water breaks sooner than expected, crisis ensues at the precinct. Meanwhile, due to an internet outage, Amy and Charles must process all the paperwork by hand to avoid the bullpen from overflowing with perps and Holt is forced to confront his ex-boyfriend.
In an attempt to solve an international case, Jake and Rosa are forced to work with a pair of Swedish cops and things get very competitive, very quickly. Meanwhile, Amy and Terry offer to help Gina prepare for a big test and Holt enlists Charles to sub in as his squash partner for an annual tournament.
Jake, Charles and Gina are involved in a real-life “Die Hard” situation while off-duty on Christmas Eve, and Terry must leave his family celebration to try to save his squad. Meanwhile, Amy tries to prove she’s just as tough as Holt and Rosa.
Charles and Genevieve want to take their relationship to a new level, but his ex-wife, Eleanor, steamrolls their plans. Meanwhile, Amy asks Terry to write a recommendation letter with disastrous results, and Holt and Rosa enlist Gina’s help to solve a case.
When Captain Holt and Jake accidentally contract the mumps during an investigation, they decide to be quarantined together in hopes of still solving the case. Meanwhile, Rosa tries to help Boyle through a mourning process, and Terry is forced to clean up Hitchcock and Scully’s mess.
Jake and Amy are excited to go on their first real vacation together, but Amy’s perfectly planned cruise ship itinerary is thwarted when they discover an old adversary is on board with them. Meanwhile, Gina and Terry help Captain Holt survive a visit from his sister, Debbie, and Charles and Rosa vie for the same apartment.
On his birthday, Jake brings Amy to meet his mother, but a surprise appearance by his dad throws a wrench in his special day. Meanwhile, Rosa and Charles struggle with a new mandate regarding body cams while on a stakeout with Terry, and Gina forgets to inform the precinct about an important plan of Holt’s.
The Nine-Nine host the detectives from the Nine-Eight, their neighboring precinct, reuniting Jake with his old partner. Charles is immediately jealous and tries to reclaim his best friend status with Jake. Meanwhile, the rest of the precinct tries to be welcoming to the Nine-Eight, but it doesn’t go as well as they had planned.
When Jake insults Hitchcock and Scully's work ethic in the precinct, they force their way into one of his cases in attempt to prove themselves. Meanwhile, Amy and Gina help Rosa conquer one of her biggest fears, and Holt and Boyle work a celebrity case.
When an unstable detective returns to the Nine-Nine after years undercover, Jake doesn’t know what to make of him. Meanwhile, Charles’ rebellious behavior pits him against the precinct’s custodian, and Holt enlists Gina’s help in directing a “fun and informational” video starring himself and Rosa.
Holt allows Amy and Jake to house-sit for him while he visits Kevin in Paris, but mayhem ensues when Holt’s beloved dog, Cheddar, goes missing under their watch. Meanwhile, a romantic fling between Adrian Pimento and Rosa disrupts Terry and the rest of the precinct.
In an attempt to prove to his old precinct that he’s not a joke, Terry enlists Jake’s help in solving a case from his past. Meanwhile, Adrian moves in with Charles, with mixed results, and Amy invites herself to a hyper-competitive training exercise with Holt and Rosa
Rosa enlists Jake to help change Terry’s disapproving opinion about her fast-moving relationship with Adrian Pimento. But their love for each other is put on hold when Pimento thinks someone from his past is trying to kill him.
In an attempt to get information on a criminal operation, Amy has to go undercover at a women’s prison and befriend one of the prisoners. Meanwhile back at the precinct, Holt and the team plan a fake funeral in an attempt to catch a hitman.
With Pimento’s life still in peril, Captain Holt calls on an old friend in the FBI to help with a seemingly impossible heist. Meanwhile Amy makes a breakthrough while undercover, and Terry and Gina discover an information leak in the Nine-Nine.