Based on the DC character, Supergirl aka Kara Zor-El (Melissa Benoist), decides to embrace her superhuman abilities and become the hero she was always meant to be. When she was 12 years old, Kara Zor-El escaped the doomed planet Krypton and was sent to earth where she was protected and raised by her foster parents, Jeremiah (Dean Cain) and Eliza Danvers (Helen Slater) and her foster sister, Alex (Chyler Leigh). Under their supervision, Kara learned to conceal the phenomenal powers she shares with her famous cousin, Superman (Tyler Hoechlin), in order to keep her identity a secret.
Years later, Kara was living a “normal” life in National City, assisting media mogul and fierce taskmaster Cat Grant (Calista Flockhart) and working with her famous friend, photographer James Olsen (Mehcad Brooks), who Grant hired away from Metropolis’s Daily Planet. When Alex’s life was threatened in a plane crash, Kara took to the sky to rescue her. In the aftermath, Kara decided she could no longer sit on the sidelines and came out as Supergirl. She now balances her job as a reporter at CatCo Worldwide Media with her work at the Department of Extra-Normal Operations (DEO), a super-secret government agency run by J’onn J’onzz/the Martian Manhunter (David Harewood), where Alex also works, as does Kara’s good friend Winn Schott (Jeremy L. Jordan). In Season One, Supergirl soared – fighting crime and battling various villains. In Season Two, Supergirl continued to come into her own as America’s hero, while finding a new best friend in Lex Luthor’s sister, Lena Luthor (Katie McGrath) and finding love with a rakish alien Mon-El (Chris Wood), who she inspired to be a hero. In the end though, Kara was forced to sacrifice this love in order to save National City from an alien invasion.
Now, in Season Three, Kara is grappling with the sacrifices she’s made and deciding if she should give up her human identity altogether. Being human and vulnerable is hard. Maybe she’s better off embracing her alien DNA and only being the “Girl of Steel.” As Kara struggles with her path forward, she continues to work with the DEO to battle all threats to National City, including new villains, Morgan Edge (Adrian Pasdar), and the “Worldkiller,” known as Reign (Odette Annable).