After 12 years of keeping her powers a secret on Earth, Kara Zor-El, Superman's cousin, decides to finally embrace her superhuman abilities and be the hero she was always meant to be.

When Kara’s attempts to help National City don't go according to plan, she must put aside the doubts that she -- and the city's media -- has about her abilities in order to capture an escapee from the Kryptonian prison, Fort Rozz. Also, Cat pressures James to use his connection to Superman to get her an interview with Supergirl.

Kara's Thanksgiving may be ruined when she suspects her foster mother, Dr. Danvers, who is coming to town, disapproves of her new role as a superhero. Also, when an accident transforms a volatile CatCo employee into the villainous Livewire, she targets Cat and Supergirl.

Kara goes toe-to-toe with Astra when her aunt challenges Kara’s beliefs about her mother. Also, Cat is threatened with being removed as the CEO of CatCo after a hacker exposes her private and damaging emails.

Kara travels to Superman’s Fortress of Solitude in hopes of learning how to defeat Indigo, a dangerous being who can transport via the Internet and who has a connection to Kara’s past. Also, James’s relationship with Lucy reaches a crossroads.

J'onn J'onzz reveals the details of meeting Kara and Alex's father, Dr. Jeremiah Danvers, and assuming Hank Henshaw's identity. Also, Kara debates trusting someone new with her secret identity and Siobhan plots against Kara.

Supergirl is forced to do battle with an unexpected foe and must risk everything – including her life – to prevent Non and Indigo from destroying every person on the planet.

Alex is kidnapped and the kidnapper threatens to kill her unless Supergirl releases a notorious criminal from prison. Supergirl and Maggie have always had different approaches to apprehending criminals but this time they must work together to save Alex. Meanwhile, Rhea has an interesting proposal for Lena.