Brooklyn Nine-Nine took the world by storm when it premiered in 2013 and despite the show being dropped by Fox (strangely after it's highest-rated season ever) the cop-comedy was picked back up by NBC and is stronger than ever as it heads toward it's eighth season.
While the show has always produced steady ratings, Brooklyn 99 season premiere's are special as every single season has ended on a cliffhanger, always leaving fans craving for the first taste of a new season.
Pilot/Season 1 (7.8)
The episode that began it all set the 99th precinct up perfectly for success - the show introduced audience's to their diverse cast of detectives and officers working in Brooklyn as they get assigned a new captain, Raymond Holt. The by-the-book captain starts to polish all of the rough edges that the precinct has (mainly Detective Jake Peralta) and does his best to turn the 99 into the best precinct in the city. However, Detective Peralta is anything but by-the-book and immediately clashes with his new C.O. as he refuses to take his job seriously. The rest of the main ensemble fill out the show perfectly as they end the first episode with all of the detectives, and their new captain, catching a perp together - and they look good doing it.
Undercover/Season 2 (8.2)
Cliffhangers - lots and lots of cliffhangers. The first season ended with Jake being recruited by the FBI to go undercover and infiltrate a crime-family, and Brooklyn 99's sophomore season picked up about 6 months later when Jake had completed his mission and gotten all of the dirt he needed on the family.
Unfortunately, during the arrest and search, one of the members of the crime-family gets away and Jake (already having blown his cover) tries to go back under in order to find the guy - and nearly gets himself killed in the process. Sadly, the member of the family still manages to get away and Jake learns (and accepts) that there are things in life that he just can't control.
Coral Palms, Part 1/Season 4 (8.2)
Season 3 ended with the 99 bringing down Jimmy "The Butcher" Figgis' entire crime-syndicate and Jake getting a call from Figgis himself where he informed Jake that he was going to kill both him and Holt. Fast-forward six months and Jake and Holt have been living in Florida for the past half-year in the witness-protection program while Homeland Security looks for Figgis. Miserable and sick of being in Florida, Jake tries to work the case on his own (which is forbidden) and gets caught by Holt, who then hides all of Jake's materials so he can no longer work the case. However, after a series of events, Holt realizes that he is on Jake's side, that he's tired of living in Florida as well, and the two post a video of themselves online in order to bait Figgis into finding them instead.
Manhunter/Season 7 (8.2)
The season 6 ending might not have been a true cliffhanger, but it certainly left fans wondering what was going to happen with Holt when he got demoted from Captain to a mere beat-cop. The episode begins with Jake in charge of a manhunt, only things get awkward and uncomfortable when Holt ends up under Jake's command (a situation neither of them are comfortable with) and Holt winds up not listening to anything Jake says and carries along on his own. In the end, it turns out that Holt was right about the killer all along and finds him before anybody else... but gets himself held at gunpoint in the process. The 99 show up and save their former captain and it helps everybody settle into their new roles quite nicely.
New Captain/Season 3 (8.3)
Instead of a demotion (like season 6), season 2 ended with Holt getting a promotion when Deputy Chief Wuntch transferred him to the Head of Public Relations. While a technical move upward, Holt hated his new position and didn't want to leave the 99, nor did the squad want him to go.
Nevertheless, they were faced with the obstacle of a new captain (played by Bill Hader) who turned out to be one of the most intense human beings they had ever met, forcing everybody in the precinct to work virtually around the clock with no breaks. To make matters worse, Jake and Amy officially began their relationship (good) but got caught making-out by their new captain (bad) which caused him to have a heart attack and die (worse).
The Big House, Part 1/Season 5 (8.5)
Arguably the largest cliffhanger of all the season finale's was during season 4 when Jake and Rosa were both found guilty of crimes they had been set up for. When season 5 came around, fans new exactly what to expect - Jake and Rosa in prison. They both seemed to handle their situations well (Jake befriended his cannibal cellmate and Rosa got herself thrown in solitary) while the 99 worked on bringing down Melanie Hawkins, the dirty-cop who set Jake and Rosa up. Unfortunately, Jake gets caught with contraband (Ramen) in his cell and is sent to Gen-Pop where he has to become part of a gang in order to gain protection. He gets comfortable with a crew that's run by a man named Romero and eventually earns his way into the gang... only to immediately be recruited as a snitch by the Warden to inform him of all of Romero's illegal activities.
Honeymoon/Season 6 (8.5)
Season 5 ended with both good news and a cliffhanger - Jake and Amy got married and Captain Holt got an email informing him whether or not he became Commissioner. When season 6 rolled around, Jake and Amy were still married... but the email stated that Holt would not be the new NYPD Commissioner. As a result, a depressed Holt doesn't show up to work for several days while Jake and Amy prepare to leave for their honeymoon - the only problem is that when they arrive at the get-a-way resort, they run into (surprise, surprise) Captain Holt, who had gone to the resort on a whim to get away from his problems. Jake and Amy's trip is hindered by Holt's constant depressing presence, only for Holt to abruptly announce that he's quitting the NYPD all together. Luckily, Jake and Amy manage to change his mind and convince him to stick around and keep fighting the good fight.