I went into this episode thinking it was a filler. After watching the episode, it was anything but that. Supergirl goes to her usual thing saving lives, including helping the firemen with a rescue. It is there that she is exposed to Red Kryptonite, which we discovered is synthetic made by Max Lord.
This brings out Kara’s dark side as she turns on her friends and workers. She got Siobhan fired from Catco, threw Cat from the building, and let an alien criminal go. The DEO find a way to cure her, but this is where a major moment happens – Hank Henshaw exposes himself as Martian Manhunter and stops Kara.
They shook up the status quo as Supergirl lost the trust of National City and Hank’s relationship with the DEO will likely strain. Max Lord got what he wanted in turning the city against her. I am glad they put a hold on Kara and Jimmy.
A great out-of-character episode of Supergirl.