Jake tells Debbie that someone stole 20 grams of coke and a machine gun from evidence lockup.
Everyone realizes Debbie is the culprit and arrest her. They suspect she is working with a crime boss, so Jake and Rosa stage a fake break out and convince her they're on her side.
They wait at a hotel for the crime boss to show up.
Debbie reveals that she went dirty because she was offered a million dollars, which she needs to pay for her dad's surgery.
She snorts the cocaine and starts waving around machine guns.
Back at the precinct, the squad goes through Debbie's journals.
Debbie realizes Rosa isn't really a dirty cop and knocks her out. She and Jake head to the new drop off location with Rosa tied up.
They go to a mansion and Debbie calls her mom.
Holt and Amy have a read off to see who can get through Debbie's journals the fastest.
Debbie duck tapes her mom to a chair and Jake introduces himself as her boyfriend. He tries to steal her gun when they lean in to kiss, but she knocks him to the ground and ties him up.
The Nine-Nine find intel on Debbie's mom.
Rosa talks Debbie down by opening up to her about her parents.
Debbie helps Jake, Rosa, and the Nine-Nine take down the crime boss.
Thanks to Rosa, Debbie is only sentenced to 10 years in prison. She and Jake make a pact to never reveal that they were both beat up by Debbie when she was on coke.