Kara Danvers (Melissa Benoist) has had fights and falling-outs with her friends before, but nothing has shaken her as much as Lena Luthor (Katie McGrath) spitting in the face of their friendship and working with Lex (Jon Cryer). In the 100th episode of Supergirl, Kara will have a chance to do things over in an attempt to fix things with Lena, but it won't be as simple as she thinks.