Jake and Charles investigate a case of Hitchcock and Scully's from the 1980s; meanwhile, Amy's uniformed officers and Terry's detectives fight over limited resources.

Jake and Gina attend their 20th high school reunion. Back at the Nine-Nine, Charles helps Rosa with her love life.

Gina plays a high-stakes game of chess with Capt. Holt; Rosa and Amy take Gina out for a fancy brunch; Jake and Gina must use their wits to infiltrate a posh club.

Terry believes the Pontiac Bandit has gone back to stealing cars, but Jake tries to prove him wrong; the rest of the squad fight to keep Shaw's a police bar when some firemen stake a claim to it.

Jake and Rosa must deal with a mother in mourning when they work on a difficult murder case with confusing evidence.

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 Amy investigate a difficult "he said, she said" case of sexual assault. Holt becomes suspicious after learning his lifelong arch nemesis died in a prison transport accident.

Jake helps Amy navigate the complicated relationship she has with her brother, David. Charles introduces some drama into an undercover mission involving Terry and Holt.

A visitor from Latvia causes Charles and Jake to investigate Nikolaj's family. Holt and Amy bring in famed forensic scientist Dr. Yee to help close a case for Rosa.

Charles gets Jake involved in a case where a therapist reports one of his patients missing; Holt learns that Rosa has a new girlfriend whom everyone else has met; Amy thinks she mistakenly received a package for Terry.

Work is so busy for Jake and Amy that they end up celebrating their anniversary while standing guard over a comatose patient in the hospital.

Holt and Jake investigate a case at Kevin's university. Back at the precinct, Terry and Amy take the squad out for lunch.

Jake and the squad must track down a hacker who has infiltrated the Nine-Nine's servers; Rosa deals with relationship issues; Hitchcock and Scully attempt to cook the perfect lasagna.

When Gina returns to the Nine-Nine, Jake and Terry get drawn into her life. Holt learns that Charles' son, Nikolaj, may be a genius; Rosa copes with an injury.

In order to distract Terry from the stress of his upcoming lieutenant's exam, Jake, Holt and the squad decide to hold the annual Halloween Heist on a new date, Cinco de Mayo.

Jake and Charles investigate a dangerous serial killer. Holt continues to spar with his rival, Commissioner Kelly. Terry tries to find a way to stay at the Nine-Nine.

Desperate circumstances call for desperate measures, as Jake, Holt, Amy, Terry, Rosa and Charles must ally themselves with old enemies.