Charles brings Jake into a case when a therapist reports one of his patients missing; Holt finds out Rosa has a new girlfriend that everyone else has met; Amy believes she has accidentally received a package meant for Terry.
Charlie and Jake investigate Nikolaj's family when a visitor from Latvia shows up unexpectedly. Meanwhile, Holt and Amy request famed forensic scientist Dr Yee's help to solve a case for Rosa.
Jake helps Amy manoeuvre the tricky relationship she has with her brother David. Meanwhile, Charles works hard to bring the drama to an undercover operation with Terry and Holt.
Jake and Amy team up to investigate a difficult `he said, she said' case. Plus, when Holt's lifelong enemy dies in a prison transport accident, he grows increasingly suspicious.
Jake and Holt clash over the merits of a new hire in the 99th precinct; Terry, Amy, Rosa and Charles try to do something about the cluttered bullpen.
Jake and Rosa work a crime scene as they seek to solve a difficult murder case with confusing evidence, while also dealing with a mother in mourning.
Terry believes the Pontiac Bandit is stealing cars again, but Jake is convinced his friend wouldn't do that; the rest of the squad fight to keep Shaw's a police bar after some firemen stake their claim to it.
Gina and Captain Holt play a high stakes game of chess, Jake and Gina use their wits to infiltrate a posh club, and Gina is taken out for a fancy brunch by Amy and Rosa.
Jake and Gina revisit their past when they attend their 20th high school reunion with Amy; at the Nine-Nine, Charles helps Rosa with a thorny problem concerning her love life; Holt, Terry, Hitchcock and Scully get caught up in an acoustical dilemma.
Jake and Charles investigate one of Hitchcock and Scully's cases from the 1980s, and Amy's uniformed officers and Terry's detectives fight over limited resources..
Jake and Amy go on their honeymoon, and Captain Holt finds out whether he is the new commissioner of the NYPD.
Jake and Amy's wedding day is threatened; Charles and the whole squad rush to save it; Holt hesitates to open the email indicating if he won his campaign for commissioner; Terry gently pushes Rosa toward a potential love interest.
Diaz and Santiago team up to take down a ruthless killer who has managed to elude them for seven years. Jeffords helps Peralta with wedding duties. Captain Holt and his rival Olivia Crawford try to convince each other to step down from the campaign.
Rosa responds to an active shooter alert; the rest of the squad is forced to stay back; Jake frantically brainstorms ways to offer his assistance; Terry faces an existential crisis; Gina and Amy try to be useful by fixing Rosa's broken toilet.
For Jake's bachelor party celebrations, Charles decides to plan an elaborate scavenger hunt, but the day goes awry when the guys decide to take short cuts instead; Amy's bachelorette party escalates when a secret affair is revealed.
When a fire destroys Charles' food truck, Pimento unexpectedly shows up to the scene as the insurance agent; Rosa helps Amy to see that it's okay to get excited about picking her wedding dress; Gina and Terry coach Holt in the art of social media
Peralta invites his newly discovered half-sister Kate to come and stay with him in New York, but he and Santiago soon realise she is a bit of a nightmare. They have to quickly come up with a way to get her home.
Jake and Charles get tied up in a pyramid scheme and must find a way to sever their contracts. Jake invites his new half sister to stay with him in New York until he finds out that she is a nightmare.
Jake surprises Amy with an investigation into arson cases connected to her favourite crossword puzzle author, Gina helps Holt jazz up his commissioner candidate speech and Terry, Rosa, Hitchcock and Scully argue over who deserves the detective car.
Captain Holt sacrifices an evening at the opera to help Peralta carry out an interrogation in the hope of getting a confession from a stubborn suspect.
When Jake is asked to negotiate a hostage situation with a jewel thief, he learns that the culprit seems to be a familiar face; Gina and Amy help Charles manage the high demands of his food truck.
After Seamus threatens Kevin, Holt devises an elaborate plan to hide him in a safe house, using Jake as his guard; Kevin is miserable as the 99 works overtime to find Seamus and take him down.
The precinct looks for a loophole when Seamus Murphy returns to redeem the favour Holt owes him. They try to find a way that Holt can uphold his end of the bargain, but not break any laws.
Rosa opens up to her colleagues and fields questions, then asks Jake to help tell her parents the big news. But they ignore what she tells them and stick with their old views.
The precinct travel to Los Angeles for a funeral. With applications being taken for Chief Commissioner of the NYPD, Jake tries to get Holt back to New York so he can interview for the job. Amy stays with estranged Boyle family members.
An author's latest manuscript is stolen; Terry, Jake and Rosa go under cover at a fantasy fiction convention to find the culprit; Terry admits he's been writing a book; Holt, Amy and Charles take a forensics course.
Jake and Amy try to use Thanksgiving dinner as an opportunity for their parents to bond. Holt's Thanksgiving pie goes missing, and he mounts a search for the culprit.
The unwelcome "Vulture" returns and threatens to take something away from Jake and Amy; Boyle and Rosa must find a missing NYPD horse; Holt challenges Terry to be less image conscious.
Jake and Terry must go under cover at an illegal gambling club to catch an infamous arms dealer; Holt teaches them the art of poker, but his addiction resurfaces; Boyle buys a food truck that was formerly used in a brutal string of murders.
The precinct embarks on its fifth annual Halloween Heist. Everybody has a plan, no one is safe, and relationships and friendships are sorely tested.
