In her fortress room, the Alura program explains Kara’s power loss to her. She says that her powers should return soon, and that she should lean on those she trusts in the meantime. Kara thanks her.
Kara is worried that it’s been a couple of days and she hasn’t recovered her powers yet.
Henshaw asks her how she’s doing, and Kara says fine; Alex says she should go enjoy being human for a day. Henshaw tells Alex to hurry back to help with “an unruly guest.”
After Henshaw leaves, Alex continues to tell Kara that she’s suspicious of Hank and she can’t trust him — that she knows he’s hiding something.
At work, Kara has a cold. She explains to Winn that she “blew out” her powers fighting Red Tornado. Cat comes into work demanding to know who’s sneezing, and tells Kara to go home.
At a DEO facility, an alien keeps trying to blast his way out of a glass cage. He identifies himself as Jemm, conqueror of 12 worlds, among other things. Henshaw isn’t impressed, and tells him that he’s not particularly worried about Jemm trying to use his psychic powers…since the cell has neural shielding. Jemm threatens to “grind Henshaw’s loved ones to dust,” and Henshaw says there are none left to grind.
Outside CatCo, Kara and James bump into one another. He says he and Lucy are getting a place together, and Kara feigns enthusiasm. She sneezes and James guesses it’s the solar flare power that blew them out.
As they’re discussing that “the world can survive without Supergirl for one day,” an earthquake hits and tears up the street they’re on. James has to save Kara from being hit by a car.
While Alex and Henshaw are preparing to clean Jemm’s cage, the earthquake hits and they lose power. Jemm escapes.
Near CatCo, James uses his shirt to make a sling for Kara’s arm, which he worries might be broken. The city around them is in mayhem.
Alex calls Kara from the DEO and tells her to call as soon as her powers come back.
Cat comes out and tells anyone who wants to be with their families to go home. She takes a picture of whoever does, and then insists whoever is still there needs to get the network back online. In spite of a four-hour estimate, Winn does so in moments.
At the DEO, Henshaw and Alex seek out Alura for advice, and she gathers a team to go after Jemm with psychic disruptor helmets. He leaves Alex behind to keep an eye on the main room, saying that he needs someone on the other end he can trust.
At CatCo, they see Max Lord on TV attacking Supergirl for not being there, and Kara decides she and James are going to go stop him from spreading panic.
At the DEO, Jemm takes out the two men with Henshaw after Henshaw himself vanishes.
On the streets of National City, Olsen and Kara come to see Lord. She tells Max that people need hope instead of fear, but Lord says he’s just countering Cat’s Supergirl branding with his own, so that people realize that people can help them, not aliens. He says he believes Supergirl has lost her powers permanently.
At the DEO, Henshaw comes into the main room and tells Alex that Jemm read the mind of the head of security and has the ability to open any cell in the place. He is going after Jemm with the last neural inhibitor, and needs Alex to hold down the fort.
On the streets, Lord helps a man who’s on the ground with a heart attack; his daughter wonders where Supergirl is but Lord says he’s their best bet.
On the street, the man who has collapsed is likely to die; he lacerated a vein, and they can’t find which one without an x-ray. Kara tries to use her x-ray vision, but it won’t work. Max gives up and leaves.
At the DEO, Alex tells another agent that she doesn’t trust Henshaw, and that they need to go take care of Jemm themselves.
At CatCo, Winn can’t get the live feed in Cat’s office to work. She threatens, and then lectures him. Finally, he figures it out, and she sends him to find somebody to do her makeup.
Outside, Kara cries over her inability to help the man in the street. James comes to comfort her, She tells him that she’s heartbroken to have the best weeks of her life, and her ability to do something positive, taken away. James tries to talk her out of it, but she continues to spiral, wondering if Max is right about her powers. James tells her that not even Superman can save everyone, but a real hero never stops trying.
Just then, she hears a stick-up in progress and, over James’s objections, goes to get her costume.
In the hallway at the DEO, Alex and the other agent recover the neural inhibitors from the fallen agents, but Jemm starts mind-controlling Donovan before he can get his on. He tries his best to resist Jemm but points his gun at Alex and tells her to run.
Supergirl walks into a store as it’s being robbed and tells the robber she doesn’t want to hurt these people.
On the air, Cat calls for people to rise up and be better in the face of the crisis. She uses Supergirl as a rallying cry, while Supergirl herself talks the robber out of it, saying she believes that people are better than this. As she does so, James takes the photo of the man handing over his gun.
At the DEO, Alex works her way through the halls and is tackled into a room by Henshaw. She admits Donovan is dead, and then gets a call from him…but it’s really Jemm, which Henshaw knows. Jemm says he plans to free the prisoners. Henshaw starts preparing to leave. the control room, but Alex makes him handcuff himself to a wall, calls Jemm and tells him to come to the control room.
At CatCo, James and Kara talk about the picture he took of her, and she asks what his first photo was. He says it was of his father, right before he left for the Gulf War and never came home. After that, he said, he never put the camera down. He says that when you take a picture of someone, you capture permanently the truth of a given moment. He tells her that she can remember from this photo that she doesn’t need powers to be a hero. She hugs him, and Winn walks in with Superman’s DEO file. He tells Kara that she might get her powers back if they’re kickstarted by an adrenaline rush. He walks out upset.
Kara chases after Winn, trying to calm him down, and Winn tells her that James has a girlfriend, and that she won’t ever have a normal life once she gets her powers back. There are a pair of explosions, which Kara hears and realizes it’s probably the gas line. Winn calls the people above them in the skyscraper and Kara starts trying to figure out how to get them down.
At the DEO, Jemm comes looking for Alex, who has a gun trained on him. He commands her to show herself, but she shoots him instead, then sets off some explosions. He tries to blast her with a beam from the gem in his forehead, but it misses her and she keeps shooting at him, finally knocking the gem out. He keeps coming and she keeps shooting, but eventually he knocks her down and is going after her. Suddenly, a scaffold falls down in front of him and he’s tackled by…something. Once Jemm is unconscious, it’s clear that it’s Henshaw, who turns on the lights and tells Alex he’s not the enemy.
At CatCo, James is going to try and scale the elevator shaft to help the people upstairs. Kara objects, but he goes anyway, since the people above can’t get it open themselves. While Kara and Winn watch, James forces the doors open and evacuates the floor. He’s the last one left above when another blast rocks the building and he falls, saving himself on the elevator cables.
Watching James fail to reach for the ladder and about to fall to his death, Kara’s powers return. She can feel her strength returning, and then flies to save him. James and Winn send her out to help the city at large.
Supergirl saves a falling school bus, puts out a high-rise fire and flies over the head of an exasperated Max Lord.
Alex calls her, and tells her that they’re all okay at the DEO, and that they’ll talk soon.
She goes into a closed room with Henshaw. where he tells her that he isn’t Hank Henshaw; Henshaw died at the same time as her father. The DEO was tracking a lost alien, who Henshaw found in Peru. Jeremiah Danvers objected and tried to stop Henshaw from killing the alien — which was a refugee, the sole survivor of a lost world, not a threat. Henshaw was obsessed, and Jeremiah died trying to stop Henshaw. He tells her that Danvers died a hero, and Alex figures out that Henshaw is the alien.
He explains that he’s a shapeshifter, who assumed Henshaw’s identity to reform the DEO, and that he promised Danvers he would take care of his daughter, and he recruited her to protect her as his own child.
He tells her that he is J’Onn J’Onzz, the sole survivor of Mars.
At CatCo, Kara invites Winn to her home, but he declines, saying he’s never disappointed in Supergirl, but he was disappointed in her.
Later that night, Supergirl arrives outside Cat’s window, where she demands to know why Supergirl abandoned them. Supergirl tells Cat that they don’t always need a Supergirl: that Cat inspired both humanity, and Supergirl.
As she leaves, she’s attacked by three Kryptonians, including Astra.