Season synopsis
Contains spoilers for this season and earlier seasons.
Holt's commissioner cliffhanger resolves badly: John Kelly gets the job, leaving Holt depressed and unsure what his career can still become. Jake and Amy try to draw him back into precinct life, then support him when he challenges Kelly's policies. The new commissioner responds by targeting the Nine-Nine. His anonymous tip app looks like a crime-fighting tool, but Jake and Holt discover it is being used to conduct illegal surveillance on New Yorkers. Gina leaves the precinct after arranging personal goodbyes with her coworkers.
The squad cannot prove what Kelly is doing through ordinary channels, so Jake gathers an unlikely team that includes old rivals and former captains. They stage a fake kidnapping to make Kelly deploy the wiretap system, while Wuntch helps Holt plant a bug. When their first plan falters, Wuntch and Jake run a second one without telling Holt: Wuntch copies the contents of Kelly's phone. The evidence exposes the commissioner, and Kelly loses his job, though he avoids arrest and moves into private-sector work.
Wuntch becomes acting commissioner and uses her first act to demote Holt to patrol duty, pointing out that he served only a month as a patrol officer before becoming a detective. That leaves Holt back on the street while Terry's lieutenant promotion creates a separate budget problem. Wuntch's decision to move Holt frees enough money for Terry's raise, keeping him at the Nine-Nine instead of transferring to Staten Island. Jake and Amy also wrestle with whether parenthood fits their lives together.