Supergirl - Season 3 - Eps 12: For Good
Someone tries to kill Morgan Edge and he barely survives. He accuses Lena of being behind the attempt and vows to destroy her. When Lena fears her hatred for Morgan will take her to the Luthor dark side, Kara steps in to help her friend. Meanwhile, after Sam realizes she’s losing time, she confides in Alex who decides to run some medical tests to see if she can find out what’s going on with her new friend.
About Supergirl

Title: Supergirl
First Air Date: 2015-10-26
Last Air Date: 2021-11-09
Status: Ended
Rating: 7.306/10 (from 4223 votes)
Language: EN
Seasons: 6
Total Episodes: 126
Network: CBS The CW
Genres: Drama, Sci-Fi & Fantasy, Action & Adventure
Production Companies: DC Entertainment, Berlanti Productions, Warner Bros. Television
Synopsis
Twenty-four-year-old Kara Zor-El, who was taken in by the Danvers family when she was 13 after being sent away from Krypton, must learn to embrace her powers after previously hiding them. The Danvers teach her to be careful with her powers, until she has to reveal them during an unexpected disaster, setting her on her journey of heroism.
Cast

Melissa Benoist
Kara Danvers / Supergirl / Kara Zor-El

Chyler Leigh
Alex Danvers / Sentinel

David Harewood
J'onn J'onzz / Martian Manhunter

Katie McGrath
Lena Luthor

Jesse Rath
Querl 'Brainy' Dox / Brainiac-5

Nicole Maines
Nia Nal / Dreamer

Azie Tesfai
Kelly Olsen / Guardian

Julie Gonzalo
Andrea Rojas / Acrata

Staz Nair
William Dey

Peta Sergeant
Nyxlygsptlnz / 'Nyxly'