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..