The episode begins where the last one ended — with a Kryptonite-armed Alex facing off against Supergirl. Kara won’t fight back, so Alex is getting the better of her, until Alex’s mom shows up with J’Onn, to talk her out of it, saying that her father believed in her and begging Alex to beat the mental conditioning. It works, with Alex tossing away the Kryptonite sword and turning off her power suit, hugging her mom and saying she’s sorry.
She apologizes to Kara, too, and then they get into the broadcast center, where Cat has faith in Kara’s ability to break the connection between the people of National City and Myriad.
They start the broadcast, and Supergirl addresses the people, with difficulty at first but then she gets into a rhythm, talking about the importance of retaining strength and hope. She says she lost everything when she was young, and she used to be sad and alone before she discovered that there is love in the world.
Winn, at his desk, suddenly becomes himself again, seeing a series of visions about Supergirl. He heads to James, who has had the same experience.
Kara continues her speech, appearing on screens all around the city, with the S-shield showing up on everyone’s phones. She manages to break the spell.
At his hideout, Non is furious that he’s failed Astra, but Indigo tells him that what he has to do is simply kill the humans and leave Kara behind, so they can conquer other worlds without Kryptonian protectors.
At CatCo the next day, James and Winn both approach Kara to apologize for what they said and did while under the influence of Indigo. Kara hugs them and says they’re fine. She feels guilty about the coworker who died, but James and Winn try to encourage her about it.
James wants to talk about the kiss that happened right before Myriad struck, so Winn excuses himself. Before they can start talking, Cat interrupts their conversation for a meeting.
At the DEO, Lucy is pretty upset while the cleaning crews work their magic. Jo’s is in the med bay when General Lane approaches. He hugs his daughter — apparently Superman is still down for the count, and nobody knows why. General Lane orders his soldiers to cuff J’Onn, over Lucy’s objections. She says that he’s pushing her away, just like he did Lois, and goes to apologize to J’Onn for his treatment. J’Onn tells her it’s fine — that General Lane is only doing what he thinks is right.
In Alex’s lab, Eliza asks why J’Onn and Alex came to see her in Middle, and then wouldn’t tell her. Alex reveals that Jeremiah is still alive and a prisoner of Cadmus.
Lord comes to see them, and tells the team that the Myriad wave keeps rising — he thinks it’s designed to kill everybody by overloading their brains.
Max briefs the DEO team and Supergirl, saying that the way they’re raising the waves on Myriad is “like using an uzi on a mosquito,” and that they have about four hours before it becomes fatal.
An agent summons Alex and Lucy to the armory; Max tells Supergirl that they need Superman and J’Onn to be confident about beating the Khryptonians, that he doesn’t believe she can do it alone. He says it’s a suicide mission, and she makes him promise not to tell Alex.
At CatCo, Kara gets to work to find Winn already with a headache. She thanks him for everything he does for Team Supergirl. She goes in to see Cat with her lunch order.
Cat asks her to get her an herbal juice, and before Kara leaves the office, she pours out her heart to Cat, as well. Cat asks her what that was all about, but accepts Kara’s “Im just seizing the day” answer.
In James’s office, he asks to finish the conversation from earlier. She says maybe there’s a reason they’re always being interrupted — that they’re not meant to be. She tells him that she knows they could have been happy together, but they missed their chance. She wants him to find happiness, and find someone who appreciates him. Before she can leave, he asks her why she’s saying this, and she tells him that she cares about him a lot, and she has to go.
At the DEO, she goes to see J’Onn. James had already called Lucy to tell her that Supergirl was acting like she was saying good-bye. She tells J’Onn that she’s just being cautious. She promises to save the Earth, but she doesn’t know if she can get out alive. She didn’t say what she needed to before the end of Krypton, and that’s why she’s doing it now.
J’Onn tells her not to give up, but Kara says that she’s not giving up — that she’s just at peace with what happens if she dies saving people. She kisses him on the forehead.
Max reveals that he’s located the Kryptonians by way of the Omegahedron. They’ve found a spot in Nevada, which General Lane says is actually Fort Rozz. Supergirl is heading out to take the mission — and J’Onn insists he’s going, too, over the General’s objection. Alex tell them both to be careful as they leave. Jo’s notes that she didn’t say good-bye to her sister, but Supergirl tells him if she did she’d never leave.
Near Fort Rozz, Supergirl and J’Onn square off against Indigo and Non, with the rest of the prisoners already in their sleeping pods, preparing for a journey through space. The ticking clock is at 6 minutes, and humans are starting to be in serious pain all over National City (as well as at the DEO).
Indigo stabs J’Onn in the side, and Non smashes Supergirl into the ground. As Indigo is about to kill J’Onn, he instead lifts her over his head and tears her in half. Meanwhile, Supergirl and Non square off with heat vision. Suddenly, Non abruptly collapses.
What’s left of Indigo tells the pair that they won’t be able to get Fort Rozz airborne or stop the signal — no longer coming from the Omegahedron — from continuing to increase. She says that all they can do is watch the world die, and then she deactivates.
With under four minutes to doomsday, the Lanes make peace. Supergirl calls into the DEO to tell her she’s flying Fort Rozz into space herself to get rid of the Myriad wave.
Alex tells her that she can’t, that she’ll die, but Supergirl makes her promise to tell Jeremiah about what a great life the Danvers gave her. They sign off, saying they love each other.
Beneath Fort Rozz, Supergirl positions herself to hurl it into space. Jo’s looks on, too injured to help, while the prison soars into the air under Kara’s power. She takes it into space, then lets go once it’s free of Earth’s atmosphere, and starts to float, losing consciousness. As she does, the ship that brought her to Earth approaches, with Alex at the controls.
Supergirl wakes up in the med bay at the DEO, her mission accomplished and Alex pleased to deliver the news. She gives Kara back a Kryptonian necklace that Supergirl had given her for safe keeping.
General Lane comes to present the news to J’Onn that the President has agreed to pardon J’Onn and put him back in control of the DEO. He gives a speech, saying that he plans to work with Lucy.
At CatCo, Kara gets a message from Clark, who feels hungover but otherwise fine. Cat comes to Kara’s desk and collects her things, making her feel like she might be fired. Instead, she brings her to a private office, saying that Kara is the best assistant she’s ever had, which is why she has to give her up. Kara asks what her new job is, and Cat says Kara should present a plan to Cat for what job she wants at the company. As she leaves, she pronounces Kara’s name correctly for the first time.
At Kara’s apartment, they’re setting the table for dinner when James arrives. He pulls Kara aside and presents her with a framed photo he took of her — not as Supergirl but as Kara. He kisses her, which is interrupted by Alex, who asks her to do “the trick.” Kara uses her strength to gently squeeze a champagne bottle until the cork pops out. They give a toast to family…but before they can get a drink, something hurtles through the air outside. When Kara and J’Onn go to check into it, it’s a Kryptonian pod like hers…and she’s shocked to see who’s inside when she opens it.