The episode opens with Supergirl being trained with the DEO. They’re shooting missiles at her, running her ragged, before Kara is called away to deal with a massive fire at the port. After trying to blow out the fire and simply making the fire worse, she pushes an oil tanker — potentially a giant bomb in this circumstance — away from the dock to safety…but she cracks its bow and causes an oil spill.
The next morning, she arrives early at work, smelling like burning oil, and Maxwell Lord is on television saying they don’t want a Supergirl in National City. Cat immediately calls a meeting to complain about Supergirl. She wants an interview with Supergirl, and insists James call on Superman to make it happen.
In the lobby afterwards, Kara tells James she doesn’t want to do the interview — she thinks Cat would recognize her. He says she wouldn’t, because he saw for years with Clark the way nobody really pays attention. He gives Kara a little pep talk about saving the city. He tells her not to worry about the interview.
At a chemical plant, a couple of security guards are debating Supergirl’s role in town when they see an intruder. He turns on them, revealing himself to be an alien and chasing down and then killing one.
Later, the DEO and Supergirl meet at the plant. When one of the DEO techs pulls a long, bony, thorn-like claw/blade out of the dead man, Supergirl flashes back to her childhood on Krypton, remembering an alien race called Hellgrammites which produce a similar protrusion in their victims. She tells the DEO that’s what they’re looking for. They all believe he’s stealing components to make a chemical bomb.
Henshaw sends Alex and Kara into a large room where she’s bombarded by low-grade Kryptonite to dampen her powers. The two spar, and eventually after Alex is rough on her for a while, Kara gets frustrated and storms off.
Back at CatCo, Kara brings Cat’s lunch and sees a headline Cat wrote criticizing Supergirl. Cat says Superman may have made similar mistakes when he was younger, but that Supergirl is a young woman, so she’s going to be held to different standards and needs to calm down.
Kara asks Winn to meet her in the alley, and when he goes to do so, James is there. The pair have an awkward meeting where they each try to get rid of the other, before Kara shows up in costume and reveals to each that the other knows her secret. Taking Cat’s advice, she asks them for help starting small.
Elsewhere, a pair of Kryptonians hassle the Hellgrammite, who tells them he needs to eat. They’re upset he didn’t stay hidden like the rest of his kind. Supergirl’s aunt arrives, telling the Hellgrammite he’s to be bait to lure out Kara.
There’s a montage of Supergirl doing a variety of good deeds in the community: stopping minor crimes, rescuing people and even retrieving what she thinks is going to be a cat — who names their snake Fluffy? — from a tree.
She heads home to meet up with the team, and answers her door when Alex comes to see her. Later, when they’re alone, Alex is upset that she told James and Winn who she is. The pair talk about the recent changes in their lives and relationship, and Kara asks Alex to believe in her. Alex’s cell phone rings; it’s work, and she has to go.
At the DEO, Henshaw reveals there’s been a number of recent attacks on chemical plants. The DEO realize that he’s actually stealing the chemicals to eat, not to make weapons.
Back at CatCo, James tries to shake off Cat’s interview demand. She threatens to fire him if he doesn’t get her the interview in 24 hours.
That night, the DEO has set a trap for Hellgrammite, trucking a huge batch of DDT toward a storage facility. They try to take him out, but instead he shoots his barbs into all the DEO agents, killing most and injuring Henshaw. He takes Alex hostage, and shortly after that she’s face to face with Astra.
At his apartment, James tells Kara that he had hoped he would stop being just “Superman’s pal” when he relocated to a new city and a new job. She tells him that the house of El’s coat of arms was “stronger together.” She doesn’t want to operate alone like Superman does, and she wants James to be part of what she does.
Kara gets a call on her cell phone: it’s Henshaw, telling her that Alex has been abducted. Kara storms into the DEO yelling that she should have been there. She asks if he has a family, and he says he did. They’re searching the city for Alex, and Supergirl joins the hunt via air, listening to the sounds of the city until she hears her sister’s voice and darts to her side. She calls in to the DEO, giving them the location of the meet.
The voice is because she’s talking to Astra — whom she first mistakes for Alura. Astra tells her that she hopes to save humanity from themselves.
Supergirl, shocked to see her aunt alive, learns that Alura had sent her sister to Fort Rozz. She tells Kara she was exiled “for trying to save” Krypton. The pair fight, while Alex calls in to the DEO. A Hellgrammite jumps her, and the two fight, but Alex uses his own barb to stab and apparently kill him.
As Astra starts to get the upper hand against Kara, Kara uses some of the tips Alex gave her during sparring to regain control. It doesn’t last long, though; Henshaw arrives, and when Astra grabs him, he stabs her with a Kryptonite dagger. Astra flies off with a scream.
Back at the DEO, Alex and Kara reconnect, and Kara wants to be taught how to use her abilities so that she can take down Astra. Alex says the best thing about Kara is that she never let the losses she suffered as a child define her. She tells Kara there’s something she needs to show her. She brings Kara to a room at the DEO that will only open for Kara. Inside, they’ve created a living program which allows Kara to commune with her mother the way Superman does with Jor-El in the Donner movies and Man of Steel. Kara thanks Alex, who leaves, and then asks the Alura program for information about Astra.
Outside the room, Alex thanks Henshaw for his help making the room. Henshaw says it’s the least he could do for Supergirl, and as he leaves, his eyes glow.
Elsewhere, a doctor pulls the Kryptonite blade out of Astra and starts studying it, saying they might need to rethink their plans until and unless they can find a way to offset the Kryptonite.
Cat is calling James to complain that he hasn’t yet set up her interview with Supergirl, when he car is lifted into the air. Supergirl sets it down outside of town and, from the air, offers to talk to Cat.