The episode opens where the last one left off: with Kara squaring off against Astra and a pair of Kryptonians. She punches them and tries to fly away, only to discover that Astra has the Kryptonite blade, and defensive devices strapped to themselves that guard them from the Kryptonite.
Astra gives her a "join the dark side" speech, but Kara staggers away, off the side of a building, and flies out of sight.
Back at the DEO, Kara tells Henshaw and Alex what happened, and wants to run out again after her aunt. Henshaw and Alex tell her not to. Alex walks Kara out, telling her to go home and get some rest, and that they should trust Henshaw.
The next morning, the news is covering a hack of Cat's e-mail. There have been no demands made, but a number of her embarrassing secrets have been revealed. She asks her lawyers if they can just sue everyone who's running the e-mails, but they discourage her, saying it would only make the situation worse.
Kara tries to tell Cat that the story will blow over, and to fight it if she doesn't believe as much. Cat tells her to schedule a meeting with the board, and to go through her e-mails for anything incriminating. She wants only Kara's most trusted friends on this one: Olsen and Winn.
The Daily Planet is gleefully republishing the e-mails, while Kara tries to read them all with James and asks Winn to track the hack. He's rude to James, because he's jealous over the hug the other day. It's slightly awkward between James and Kara, too.
At their headquarters, Lieutenant Non tells Astra that he's upset she didn't kill her niece. Astra tries to back him down, but he's convinced she's letting Kara off light because she's family. She says "I will die before I allow another world to end before I can save it." He tells her that if Astra dies, Kara dies, and calls Astra "wife."
Later, at the DEO, Kara and Alex spar. When Kara gets the better of her, it's not enough, and she continues going after her, wanting to fight more and more but getting sloppy with anger. Alex chides her for hesitating during the fight, asking her what's going on and saying the DEO should handle the Kryptonian threat. It isn't fair to Kara to make her fight her family. She asks whether she's actually ready to kill if necessary, and Kara says that Superman doesn't kill. Kara says that won't work for Astra, who has shown she's willing to kill Kara. She asks what Kara is holding onto, and Kara says nothing, then flashes back to Krypton.
Astra goes to meet her niece, saying that Krypton is dying -- that the core is unstable and that she's trying to save it, but she's had to do some bad things to save the world. She tells her that she has to leave Krypton, but that she didn't want to go without saying goodbye. She hugs Kara, saying that she couldn't love her own child more, but their moment is interrupted when Alura comes in and tells Kara to leave them.
At CatCo, James and Kara are finding nothing that concerns Cat. She tells the board that it was bound to happen. Many of the board members ask her to take a step back and put some distance between herself and the company. One particular member of the board says he trusts Cat's judgment, and that he's sure she'll be the first to step away if things get too bad.
After the meeting, Cat tells Kara to keep looking for dirt, since Dirk Armstrong is going to be on top of whatever comes out of this. Kara listens to Armstrong with her super-hearing and hears him admitting to set Cat up.
Kara asks James to get Lucy to help them, since they can't trust Cat's legal team. Lucy advises them that they need a paper trail, or they'll make things worse. On the TVs at Noonan's, they see Astra hovering outside CatCo. Astra asks her if she'll talk to her now that she's come without backup or Kryptonite. Kara blasts her with heat vision.
The pair have a slugfest in the air over the city, until Astra runs and Supergirl gives chase, blasting her into and out of a skyscraper and then flying down to save bystanders from falling debris, which she uses to throw at Astra. Finally she ends up on the ground, Astra standing over her. Astra tells Kara that Alura was a liar, and weak, but Kara says her only weakness was letting Astra live. She pounds her around for a bit, then relents when she sees her aunt nearly in tears. Astra falls unconscious, and Kara drags her to a cell at the DEO. Alex says they'll call Kara when Astra wakes up, but Kara says not to.
At CatCo, Winn says he has a plan to get Armstrong; he's going to hack the hacker, but he wants James to go leave a bug on Armstrong's computer. Winn calls to Armstrong's office with a report that Armstrong's car is on fire, while Kara watches with her x-ray vision. James breaks into the office, but it takes longer than expected to place the bug. The corporate espionage is successful, but Kara sees Armstrong returning to his office. James takes a seat on the desk. He tells Armstrong that he's got support from James if they need to make changes given Cat's bad day. He leaves.
At the DEO, Astra produces a communicator she and Kara used to use on Krypton and tells her it's time she knew everything. She tells Kara that she kept the communicator to remind herself of what she was fighting for. She tells Kara that Alura betrayed her. Kara doesn't believe her, but then asks whether it was Kara's idea to contact her with the beacon.
She flashes back to that night, when she says Alura jailed her because she wouldn't surrender herself and Non on murder charges, but Astra says she can't do that because she's worried that Krypton is dying. Kara says she doesn't remember it and doesn't believe her. She tells Kara that Earth, too, is on the verge of ecological destruction, but that the humans won't let her. She says she's begging Kara to help her. Kara leaves, and Astra says she loves her.
Kara goes to see the Alura hologram, asking her if Alura had used her to get Astra arrested. When Kara asks whether Krypton could have been saved if Astra was right, "Alura" says "I am not programmed to give you that information." Kara breaks down crying and heat-visions the hologram, saying her mother lied to her. Alex tells her that she doesn't know what really happened, and Kara says that she knows both she and Astra "were given life sentences by my mother."
At CatCo later, she doesn't want to talk about the situation with James and Winn. No luck yet hacking Armstrong's e-mails, but James has found financial records indicating that Cat is supporting someone named Adam Foster in Opal City. James and Winn think she has a guy on the side she's paying for, but when Kara goes to see Cat, she reveals that Adam Foster is her son. His father was somebody she hadn't dated long, and who left her with the kid. She sued for custody but she lost...then she says she didn't lose, she quit, dropped the lawsuit, because she believed that she would be in his life anyway, but she determined that her child might be better off without her. Kara asks her if she would make a different decision if she could go back, but Cat says she stopped asking herself that decision years ago. She says not being there for Adam is her biggest regret, but that she doesn't feel like she has the right to call him and try to get him on her side. She says that rather than allow him to end up in the middle of a media storm, she's going to step down from CatCo.
Just before the press conference where she's about to do it, James and Winn come -- with Lucy, and the memo that incriminates Dirk. She calls him into her office, showing him the e-mail. He says his lawyers will eat her alive for hacking him, but she reminds him that since he wrote the e-mail from a company-related account, about company-related business, on a CatCo-owned computer, they're legally hers anyway. She has him escorted out by security and police.
After Kara steps away from Kara and James, James apologizes to Winn, saying he didn't realize how much he liked Kara. Winn tries to downplay it, but James says he's not in Winn's way, and that if he has feeling for Kara, he should tell her. Winn says that she's way out of his league. James tells Winn that Kara is special, and not because she's Supergirl -- that she's worth risking it for. He tells Winn he should try.
At the DEO, Henshaw asks Alex how Kara is. She says heartbroken. Henshaw and Alex don't trust what they've seen from the fight; they believe she wanted to lose. Henshaw says Kryptonians are impervious to his telepathy, but they go looking for Astra. They tell Astra to tell them what her forces are doing right now, but she says it's too late to stop it. A number of Kryptonian soldiers with Kryptonite shielding descend on Lord Technologies.
At CatCo, Kara joins Cat on the balcony, where she's having a drink. She tells Kara that she's figured out that Kara is Supergirl. She tells her to take off her glasses, and thanks her for all the help she's given her, calling her Supergirl.
Kara gets a phone call, and it's Alex, telling her Lord Technologies is under attack. Lord, though, has an anti-Kryptonian weapon he's developed. The DEO squares off against four of the five aliens, under orders to kill them all. When one of the Kryptonians punches Henshaw, they realize he isn't merely human. he trashes the Kryptonite shielding on him and then shoots him with a Kryptonite cannon, killing him. Non, though, throws off a group of "merely" human guards and goes after Alex before Kara comes for him. The two hover, flying at each other and screaming.