Kara comes in contact with this inhibitions-removing rock while helping some firemen out with a fire.
Also, lets just say Batman and Superman arent the only heroes fighting each other this month.
Supergirlstill hasnt quite mastered subtlety, so the first scene prepares us for (telegraphs) Karas personality change.

Credit: Sonja Flemming/CBS
Falling opens with Cat doing an interview on CBSsThe Talkabout what makes Supergirl so special.
The most remarkable thing about Supergirl is shes the kindest person Ive ever known, Cat says.
She is an ideal, and shes inspiring us to be our best selves.
Now, we can learn a lot from her.
(Real talk: Who was CBS trying to appeal to with this cameo fromThe Talk?)
Kiera, look at you dressing like an adult, says Cat when she sees Karas new look.
I dont really care, she says.
What are you so afraid of?
The longer the Red K remains in Karas system, the worse she gets.
Naturally, Cat fires her.
Clubbing doesnt go well at all.
Turns out James isnt into Bad Girl Kara.
It was awesome, fun, and scary at the same time, like a Kanye West Twitter rant.
At the last moment, Supergirl decides to catch her before she hits the ground.
That line was clearly her version of aGoosebumpswalkaway.
At this point, Karas personality change stops being fun and starts getting scary.
A rightfully pissed-off Alex lets him know that he turned Kara into the monster he was scared of.
As we learned fromAvengers: Age of Ultron, we all create the thing we dread.
While Maxwell gets to work on a cure, Alex heads to Karas apartment to check on her.
(This isnt a leather jacket, but I guess this will do.
Still kind of disappointed we dont get to see Kararide a motorcycle.)
Meanwhile, Cat decides that its her duty to warn National City about this new Supergirl.
Kara sees her message to the city while sitting in the bar and decides to go on a rampage.
So, the DEO heads out with Kryptonite bullets and Maxwells finished weapon.
Yes, we got a Martian Manhunter vs. Supergirl fight into tonights episode.
Although most of it was a CGI blur, I loved it nonetheless.
Afterward, Alex pleads with Hank to run away, but he stays and allows himself to be arrested.
Its so moving that Karas first concern is whether or not she killed anyone.
Alex lets her know that theyll have to work on the things Kara brought up.
Hank is stuck in a cell now.
James stops her from telling him she loves him and says he needs some space.
And, most importantly, the city she loves is now scared of her.
Seeking guidance, Supergirl visits Cat to apologize.
Cat assures her that winning the citys trust will be hard, but its not impossible.
Supergirl asks if she can sit on Cats balcony for awhile, and Cat says yes.