Not only is this one of the funniest scenes in the entire season, but it's also a clever way of depicting Rue in a manic state. Zendaya and Maude Apatow play off one another beautifully in a faux good cop/bad cop routine that's a breath of fresh air amid all the heavy drama of the episode. Detective Rue is every chain-smoking cop who is getting way too old for this sh*t (which she points out during a rant to Fez, exclaiming, "I'm Morgan f*cking Freeman, and this is the beginning of the third act"), and I would absolutely watch a webseries about her adventures with Detective Howard.
But as Rue smokes cigarette after cigarette (doesn't the school have smoke detectors?) and her theories get more in depth, we realise this is spiraling into more than just a funny investigation, and Rue has entered into a serious manic episode. At one point, she stands in the middle of a sea of photos and declares to Lexi over the phone that she's never felt better in her entire life. But as Detective Howard tells Detective Bennett, "You're too close to this case."
Image Source: HBO via Giphy