After keeping her powers a secret for 12 years, Kara Zor-El, Superman's cousin, decides to embrace her abilities and be a hero.
Kara must put doubts aside as she tries to apprehend an escapee from the Kryptonian prison; Cat pressures James for an interview with Supergirl.
An enemy of Superman named Reactron targets Supergirl, testing her powers; Cat plans to run a revealing article on Supergirl.
Kara's foster mother visits for Thanksgiving; Cat and Supergirl become targets when an accident transforms a volatile CatCo employee into Livewire.
While Kara is baby-sitting Cat's son, she must also protect the city from a series of bombings; Lucy Lane (Jenna Dewan Tatum) tries to rekindle her relationship with James.
Kara goes too far during a training exercise against a military cyborg commissioned by Lucy Lane's father; Cat's judgmental mother visits; Alex asks Winn to investigate her father's death.
National City is struck by an earthquake; Alex and Hank are trapped in the DEO with a powerful alien.
Astra challenges Kara's beliefs about her mother; a hacker exposes Cat's private -- and damaging -- emails, putting her job at risk.
While Astra is held captive, her husband abducts Hanks; Cat continues to suspect that Kara is Supergirl.
Winn's father, a supervillain named Toyman, escapes from prison and contacts his son; Cat offers Lucy a position at CatCo; Alex wants Hank to uncover Maxwell Lord's plans.
A member of the alien race responsible for killing Hank's people kidnaps anti-alien Sen. Miranda Crane; Cat's estranged son visits National City.
A twisted version of Supergirl tries to destroy Kara; Cat's son (Blake Jenner) and Kara become closer.
A parasitic alien traps Kara in a dream where her home planet is intact and her family is alive; Alex, Hank and the DEO have to fend off a Kryptonian attack without Kara.
Supergirl battles with Master Jailer (Jeff Branson), who is tracking and killing escaped Fort Rozz prisoners; Cat hires an additional assistant (Italia Ricci), who tries to one-up Kara; James and Kara don't agree on the DEO's methods.
Kara travels to the Fortress of Solitude to learn how to defeat Indigo (Laura Vandervoort), who has a connection to Kara's past; James and Lucy's relationship comes to a crossroads.
After being exposed to red kryptonite, Kara turns malicious and becomes a danger to her friends and to the people of National City; Cat discusses Supergirl on "The Talk."
J'onn J'onzz discloses the details of meeting with Kara and Alex's father, Dr. Jeremiah Danvers, and the takeover of Hank Henshaw's identity; Kara must decide whether to trust someone with her secret identity; Siobhan devises a plot against Kara.
The Flash (Grant Gustin) comes from an alternative universe and aids Kara in her battle against Silver Banshee and Livewire in exchange for her help getting home.
Kara must free her friend when Non and Indigo implement mind control to turn National City citizens into their own army.