Myriad


 * For the system the title refers to, see Myriad (program).

Myriad is the nineteenth episode of the first season of Supergirl. It aired on April 11, 2016.

Synopsis
Kara must find a way to free her friends when Non and Indigo use mind control to turn National City’s citizens into their own army.

Plot
At the DEO, the entire compound are now under the influence of the Myriad project, which has also taken over National City. Non uses the mind control to order Lucy to release all prisoners except for the White Martian. When Maxima, a prisoner who had feelings for Superman at one point but now allies with Non as his new partner, makes her escape, Kara arrived to keep her from joining Non but Maxima uses a kryptonite bullet to slow her down. However, Kara does destroys the computer terminal after using the afterburners from her ship to knock out the mind-controlled DEO members and preventing the prisoners from escaping. After removing the bullet, she flies to the Fortress of Solitude to find her cousin Superman, but Kelex tells Kara that he is not on Earth and refuses to inform Kara about Myriad. She then turns to the image of Alura, who explain that Myriad was a mind-control system Astra and Non were arrested for trying to use against the people of Krypton; Kara learns from Alura that once Myriad is in effect it can't be stopped.

Back in National City, Kara is noticing everyone, even Winn and James, are now under the Myriad effect and watching Kryptonian codes on the screen, General Lane has placed the entire city under quarantine, but Kara informs him that she will help save his daughter. Cat arrived to her office, but is not affected by Myriad. Kara then gets a text from Clark to help her immediately. Unfortunately when she goes to look out the window, Superman arrived, only to be mind-controlled as well. Kara then notices Maxwell entering with a headset that protects him from Myriad, and that the earrings that Cat is now wearing also protected her from Myriad. Maxwell tells Kara and Cat that Non is using his satellites to control the humans but his real goal is to kill all Kryptonians. A move echoed by Indigo, who wants to kill Supergirl once and for all. Non believes that bringing the people of Earth together to save the world will save the world from Krypton’s fate, but Kara believes he betrayed Astra for doing this, so Non forces the CatCo employees to turn on Supergirl and after he forced them to jump to their deaths, Supergirl immediately rescues Winn and James, but is too late to save a woman nearby. A mind-controlled James and Winn tell her to accept defeat or die. Meanwhile, Alex and J'onn, posing as mother and son so they can elude authorities, arrive at Eliza's home, where after a moment to calm her down (as J'onn transformed to prove he wasn't Hank), reveal the truth about Jeremiah being alive. Eliza then informs the two about National City under quarantine and turns on the television. After a conversation over what happened and looking at pictures of Jeremiah and his daughters, J'onn gains the trust of Eliza and promises to keep a eye on Kara and Alex. Alex then gets a call from Kara, who asks about Project Cadmus, but Alex wants to return to National City to help. Kara, on the other hand, hangs up on Alex, warning her not to come or she'll be under Myriad. J'onn, however, agrees with Kara, and since he is not affected by Myriad, tells Alex to stay behind while he goes back to National City because her father still needs her, but later on and without explaining this to Eliza, both Alex and J'onn return to National City. When they return, Indigo is ready and waiting for the twosome as they're lured into a battle, with J'onn almost gaining the upper hand. Indigo managed to come back and attack J'onn and grabbing Alex. Indigo then orders a weakened J'onn to stand down or she'll kill Alex, and he does that, only to collapse, as Indigo is convinced that J'onn, being the last surviving Green Martian, has died.

Maxwell has come up with a plan to drop a Kryptonite bomb on the city, but at the risk of killing both Kryptonians and residents, which is given the green light by General Lane under the orders of the President. Despite going along with his plan, Supergirl is receiving opposition from Cat, as Maxwell demands to know whether she’s with him or not. Supergirl asks Maxwell what made him who he is now and he tells her that he knew what was going to happen to his parents, but nobody listened to him, telling her that now he rushes in just the way she does when she suits up. Cat is still upset with Supergirl for going along with Maxwell, believing that everyone is letting their fear guide them, but someone has to find the courage to stand up, adding that Supergirl inspires everyone to take a stand. This convinces Supergirl to come up with a idea. When the two arrive at Lord Technologies to convince Maxwell not to go through with the bomb but by now has begun preparing to launch it, Maxwell doesn’t want to listen to their offer, but Supergirl uses his feelings about his parents by convincing him to honor them as well as hers by making a choice that won't involve weapons.

Back at Non's secret location, he and Indigo are ready to greet Alex from having been conscious for hours, as Non tell her that he wanted her to be awake so that he could see her suffer the same way Astra died. Despite Alex telling Non that Astra lost her taste for Myriad at the end, he isn't convinced and Indigo suggests she knows how to hurt Alex and Kara. Meanwhile at a undisclosed location, Kara, Cat, and Maxwell are setting up a counter signal to Myriad which would broadcast an old analog signal from a defunct TV station Cat owns until Alex shows up. When she sees that she now wearing Kryptonite armor, Kara realizes, to her horror, that she is now mind controlled by Non. She challenges Kara to fight her to the death and Alex lunges at her.

Trivia

 * Non mentions Opal City and Central City, both of which are locations also present in the Arrow/Flash universe, with Central City first revealed to exist in the Supergirl universe in "Worlds Finest", and Opal City earlier being mentioned as where Adam Foster lived.
 * When Cat first arrives at her office, she tells Kara to tell Harrison Ford that she is not interested in dating older men, especially married men. This is a joke on the fact that Cat's actress, Calista Flockhart, is married to Harrison Ford.
 * The scene where Non threatens Kara by having James, Winn, and Kelly jump off the building is very similar to a scene from the 2015 film Insurgent, from the Divergent Series. In both, the villain (Non, Jeannie) uses mind control to intimidate the hero by having three people that the hero (Triss, Kara) cares about jump off a high ledge. Although they both managed to save two of the three, one (Kelly,  Marlene) falls to her death, shocking and guilting the hero.
 * When J'onn shoots Indigo, she drops the bullets and says "Nice try" similar to how Zoom did it in "Enter Zoom".