Meanwhile, Metallo wakes up. The doctor explains she’s from Cadmus and asks if John is ready to begin his mission. His purpose is to destroy Supergirl and Superman.
Back at the DEO, Winn alerts the team to an energy drain in the basement. Mon-El is “absorbing the electrical energy and converting it into chemical energy” to heal himself at the cellular level. Then, Supergirl invites Clark to sister night with Alex, where they watch Veep and eat Chinese.
During her first day as a reporter, Cat Grant introduces Kara to Snapper Carr. She will work under him at Cat’s magazine, but Kara doesn’t make a great first impression.
When Clark arrives for sister night, he says he’ll be returning to Metropolis soon. Unfortunately, he can’t stay any longer. It’s time to return to Lois and the Daily Planet. For their last team-up, Clark agrees to assist Supergirl with a jumper on the bridge. When they arrive on the scene, they find that the jumper is Metallo. Immediately, he blasts Superman with a kryptonite beam. Supergirl’s punches and laser vision prove to be ineffective against him. Instead, she uses a car as a shield (everyone say hello to Melissa Benoist’s biceps) to get closer to him. But this only gives him a chance to blast her at point blank range. Before he finishes her off, Superman body checks him a few blocks away.
Superman returns to the DEO and yells at Hank for letting someone steal the kryptonite. Suddenly, the monitors all over the city are taken over by Cadmus. They announce that Supergirl is the enemy and they are the antidote. Alex reminds everyone her father is at Cadmus as Hank volunteers Winn to build Superman a new suit.
The next day, Kara arrives late to the editorial meeting. Snapper fires her. Apparently, Kara doesn’t know how jobs work. She says, “this is the job I chose,” but Snapper argues that she didn’t earn it. He kicks her out of the office before he can get really sour — “leave before I channel my last divorce and emotionally break you.” Of course, Kara runs to Cat, who tells her to stand up for herself and to stop being a baby.
At this time, Cat announces that she won’t be around much longer. She’s not dying, but she’s taking a leave of absence from CatCo. She doesn’t want to swim in the same pool anymore. Kara struggles to accept the change, but Cat knows she will rise to the occasion.
While at Cadmus, John asks for another chance as they prepare to go to Phase 2.
Afterward, Superman takes Hank to the Fortress of Solitude. Hank / J’onn explains that he won’t let what happened to Mars happen to Earth. So he has to keep kryptonite on hand. However, he wants to keep the culture of Krypton alive. He even knows their language. Once Superman’s suit is scanned, they learned it contains traces of Promethean.
Meanwhile, Kara entertains the idea of moving to Metropolis. She thinks she’ll be out of everyone’s way, but Alex laments that it’s a terrible idea. They’re supposed to take care of each other. Alex said she gave up a medical career (Grey’s shout-out, right?) to join the DEO. Kara argues that Clark is the only one who understands her, but Alex reminds her that Clark abandoned her once already.
Winn isolates Metallo’s location. The Supers prepare to fight him, but it’s just a diversion. Phase 2 includes sending another guy with the Kryptonian skeleton to Metropolis.
In the destroyed Metropolis, Superman admits this was his responsibility.
While working on the Supersuits, Winn tells Alex to stop whining and “chill.” Alex realizes that kryptonite leaves a residue. So to find out who stole the kryptonite, they take a Geiger counter into the locker room. Alex tells the suspect to prepare to transport some kryptonite. As the Agent steals some kryptonite, Alex confronts him. Before she can turn him in, Cadmus shows up.
Alex asks about her father. Instead of answers, she’s offered a position in the club. Eventually, she escapes, but not before threatening them all. Once she finds her father, they’re next. Supergirl arrives to assist, and they trade apologies.
Supergirl comes up with a plan just as Winn finishes the suits. Cadmus expects them to split up and cover their own cities, but Supergirl plans to fake them out with an entire fleet. This time, when Metallo blasts Supergirl’s suit, her armor absorbs the hit. Man, I wonder what would happen if they just aimed somewhere else? Sorry, Winn, that’s a terrible design. And it gets weak with a couple of punches.
Okay, so Kara’s “fleet” is made up of just one person. Alex (and her dope suit) provides backup for Supergirl while Martian Manhunter assists Superman.
Tonight’s MVP award goes to Alex for throwing a broken pole through Metallo’s chest and impaling him. Honorable mention goes to Martian Manhunter for just putting his fist into the other guy’s chest and ripping his heart out.
After the fight, Supergirl visits Cat to say goodbye. Cat is thrilled to venture into the unknown, but I will miss her so much. Her advice and snark are so on point. Cat tries to get Supergirl’s real name but is denied. Thankfully, Cat promises to return.
James takes Cat’s place as chief. Finally, Kara takes a 500-word report to Snapper Carr on the “dual Metallo attacks” and learns to stick up to the “jerk guy.”
J’onn gives Superman the kryptonite and says goodbye to everyone. In Kryptonian, Supergirl tells Superman their adventures will continue. When he arrives in Metropolis, he sends her a message that I don’t think works in the context of cousins, but oh well.
In the last scene, Supergirl encourages Mon-El to wake up. He opens his eyes and grabs her by the throat.