There’s a mystery to solve in the Nine-Nine and the squad takes on the Mystery of the Exploding Package in a classic whodunit. Sorry, a classic who has done it. The episode starts with Jake asking Holt for a spot on his task force. He even presents a (rhyming) resume and Charles joins in rapping in the background. But their meeting is interrupted by an exploding glitter bomb. Scully thought it was a good idea to open a package not meant for him and ends up covered in red glitter. 

The squad assumes whoever did this was the victim of someone Jake pranked recently but that means anyone could be a suspect. They find a note with the word “babe” on it, so everyone turns on Amy, who denies it. Tired of the squabbling, Holt calls in an old friend named Dillman, an SFPD detective to solve the case. 

Jake decides he’s going to solve the case before Dillman to prove to Holt that he should be on the task force. He starts by finding Terry’s suspenders in his desk drawer, which are covered in red glitter, pinning Terry as the culprit. But Dillman proves Jake wrong and tells the squad that the glitter is from a science project he did with his daughters. Dillman also says the glitter is different. He knows a lot about glitter. Terry confirms that this is correct.

Dillman decides to interrogate Rosa because she wasn’t there at the time of the prank. After a long staring contest, Rosa cracks and says she was upstairs watching a soap opera. The two go back and forth about the details of the show and Dillaman eventually lets her go. Holt is really enjoying this interrogation.

 During the interrogation, Jake is working through lunch pairs and discovers that Charles had lunch with Holt. Holt admits that he offered the task force position to Charles, which upsets Jake and he storms out of the room. Boyle finds Jake in the meeting room and tells Jake to take the job because he has been trying to cut down on hours. However, Jake urges Boyle to accept the job. It’s a really great friendship moment between Jake and Boyle. 

Jake returns to the Mystery of the Exploding Package and says that Dillman was the one who did it and has lots of evidence to back it up. Dillman denies this. Dillman says that Jake is responsible for the glitter bomb and gets Holt and the rest of the squad to believe him. Holt suspends Jake. 

Jake is supposed to be suspended but he keeps working the case. He returns to the precinct and announces that Dillman was fired from the SFPD and now works at Yarn Barn. Dillman turned to Holt because he was hoping to join the task force and rejoin the NYPD. 

But both Jake and Dillman are wrong. Boyle comes in with the reveal and a whole slew of evidence that the perpetrator was one of their own. He says that the detective, Officer Booth, was trying to sabotage an ongoing investigation and intentionally ruined the evidence on Jake’s desk with the glitter bomb and framing Jake for tarnishing evidence. In a great elevator reveal, we see Officer Booth in handcuffs. Boyle really does deserve to be on the task force because as Jake points out, he’s a great detective.