A woman walks alone at night, looking over her shoulder in fear. There’s a man following her, and as she tries to escape him, another cuts her off in a dark alleyway. Luckily for her, Guardian jumps in to save the day, but after he takes the duo out, she scampers away in fear, pleading for the vigilante not to hurt her. The hero, distraught by the fear he seems to constantly cause, tells Winn that they need to call it a night. The next day, Lena and Kara meet up for lunch and the Luthor woman gushes over her newest project, as well as her new mentor’s abilities. That very mentor calls Lena just moments later, and she and Kara are forced to part ways to continue their work days.
At a nearby park, James is brooding over the previous night’s Guardian-related events, and while Winn tries to cheer him up, they’re interrupted by a telekinetic, hostile alien that seems to only want to cause distress. She ascends into the air and starts sending food trucks and various vehicles flying. Thankfully, Supergirl swoops in and catches a truck before it crashes into a nearby building, but the alien vanished before anyone could apprehend her. Her actions put the city into a state of fear, and cause members of the DEO to take note. Winn discovers that the woman is a species of alien known as “Forian,” and as J’onn, Alex, Winn, and James discuss the matter of capturing her, J’onn mentions that Supergirl and Mon-El are casing the city. James offers to help, but the Director turns him down with a very pointed comment about not needing Guardian’s skill sets for it.
Lena is enjoying her dinner with Reya, though she’s very visibly upset about not being able to solve the issue of their project. As Reya boasts about Lena’s skill, Lena simply pouts about it not being enough, because this portal could revolutionize the world, and virtually get rid of famine across the Earth. Reya offers only encouragement toward the young Luthor woman, before telling her that she was going to leave to inspect their work. As she’s leaving the restaurant, Mon-El happens to be walking down the street. He stops when he sees her, unsure of whether it’s his eyes playing tricks on him, but man bumps into him, and when he looks back toward where he’d last seen her, she was gone.
Guardian interrupts a drug deal between Brian the alien and a dealer, but before the vigilante can rough up Brian too bad, the prominently-nosed alien gives up the location of the telekinetic woman, having claimed to know where she lives. As Guardian investigates the home, a little boy tries to escape through the front door, fearful of the sudden intruder. However James calms him down when, to prove that he meant the child no harm, he takes off his mask. He touches James’ face, seemingly calmed by the fact that the man had the same skin color as him.
At the DEO, inside of an interrogation room, Alex is trying to coax the boy into speaking by offering him a cheeseburger. The boy, who we find out to be named Marcus, uses his telekinetic powers to push the plate away, unwilling to give up the location of his mom. James, J’onn, and Winn watch from the other room, where James comments that he wouldn’t talk either if he was treated the way this boy had been. Alex comes out of the room, having failed at getting Marcus to speak, but when she realizes that even through the walls, the boy is following James’ every move, she suggests that James be the one to get through to him.
Lena and Reya are in a compound just outside of National City, trying to get their portal operational. Frustrated with the lack of results, Lena turns to Reya and vents about the machine not being able to sustain the amount of power they’re trying to put in. She makes a comment about going to get Lex to solve it, considering he’s the smarter of the two. Reya quickly shuts down the negative thoughts swirling in the Luthor woman, by explaining that Lena had been too quick to think like Lex, and asked what SHE would do. The Daxamite quickly points out that Lena was focused on Lex’s thoughts of “more power,” but since she herself isn’t a woman interested in power, she needed to find her own way. That she does, and the answer to her question isn’t a matter of power, but a matter of balance.
James gives it a shot by taking Marcus with him to CatCo, where he introduces him to Kara. The boy doesn’t respond to Kara’s attempts at kindness, but the reporter takes it in stride, and kindly tells them both goodbye before returning to her work. James asks his assistant, Eve, to get he and Marcus a couple of milkshakes, as well as an order of curly fries from a nearby restaurant called Noonans, before allowing the young Forian to wander his office. The two bond over James’ collection of cameras, before both coming to the realization that their fathers were soldiers whom had passed away. Marcus finally speaks to James, and at one point asks if he can take a photo of the man, but just as he’s about to, he sees his mother’s face pop up on the t.v. screens behind him.
At the facility, Lena has found the correct formula, and after entering her new algorithms, powers up the machine. Within the CatCo walls, Marcus loses control of himself and starts tearing the building apart. Supergirl saves the day once more, by flying through and carrying Marcus away from the building. Once Lena finishes successfully testing their portal, Marcus returns to himself, and Supergirl keeps him from panicking when he realizes he’s flying. Unfortunately, the DEO has to keep him in a cell until they figure out why he lost control, and James tells J’onn that he shouldn’t have gotten involved.
Within the halls of the DEO, J’onn explains that his daughter gave him a purpose; helped make him the protector he was, and that this young boy is the answer to James’ own inner turmoil. James offers to give it one more shot, motivated by J’onn’s belief in him. Meanwhile, J’onn, Kara, Mon-El, Winn, and Alex all discuss what could be causing such a drastic change in the usually peaceful Forian species, when Winn mentions a spike in a specific kind of radiation particle. Kara mentions to the group that Lena had been working with the very same particle, and that it couldn’t be a coincidence, but when she calls Lena, Reya is the one who answers the phone.
Kara threatens the Daxamite, before putting her on speaker phone for everyone to hear. Reya refuses to give up her plans, and after the two finish squabbling, Reya hangs up before Winn can lock onto her signal. At the compound, Reya brushes off the use of Lena’s phone by claiming a telemarketer had called. James sits with Marcus in the cells and tells him about how he grew up at a school where there weren’t a lot of kids who looked like him, and when he moved to Metropolis, he made a friend out of a man who understood what it was like to be treated like an outsider. He convinces Marcus to show him where his mom is, but in order to do so, James has to take the boy out of his cell. With J’onn’s permission, Marcus, James, and Winn all pack up and go looking.
Winn had taken along a portable device that dampened the powers of, at most, two telekinetic-powered beings, which should allow them to protect both Marcus and his mother from losing control of their abilities. They soon find an issue with that however, when another ten Forians emerge from the shadows, worried and scared about what might happen to them. Meanwhile, Lena excitedly tells Reya that more trials can begin the next day, but it seems Reya has other plans. She tells Lena that no matter what, her affection for the Luthor was genuine, and that Lena truly is a wonderful being, before cranking the portal’s numbers all the way up. Marcus, his mother, and the other Forians lose control the second the portal is turned on, leaving James and Winn in mortal danger, while Supergirl, Mon-El, and J’onn bust through the ceiling of Lena’s compound and demand that it be shut off, and though Lena had tried, she wasn’t successful.
Supergirl goes to the core and attempts to destroy it, but is unable to do so. She gets into an altercation with Reya, where Lena ends up knocked out. Instead, the Kryptonian heads directly for the portal, but after another failed attempt at destroying it, she gets knocked unconscious and falls to the ground. J’onn, frustrated by the attack on his “family,” as he puts it (#BestSpaceDadEver), makes to attack Reya, but she pulls out a device that effectively stops him. Mon-El demands to know what she’d done to him, and when she explains that the device forces him to relive his worst nightmares, the Daxamite Prince draws a gun on his mother, alerting her to the fact that they’re not immune to bullets.
James tries to get through to Marcus, determined to keep his promise and protect the young boy and his mother; Winn isn’t so convinced that it’s working, and with the building coming down on them, tries to get James to leave with him. Just as all seems lost, James tells Marcus to look inside and see the courage that he sees within, and Marcus breaks through, allowing the other Forians – Who are all telepathically linked like Martians – to break free as well. Mon-El finds himself unable to take his mother’s life, despite everything she’d done, and she explains to him her plans: Thousands of Daxamites had escaped their planet, so she’d called them to Earth in the hopes of making “New Daxam.” The episode ends with Reya transporting both Mon-El and Lena to her ship, and hundreds of Daxamite ships hovering over the span of National City.