Fight or Flight

Plot
Supergirl starts her interview with Cat Grant, during which the latter questions her about her origin, powers, and whereabouts, all while recording the interview. Eventually, Kara became frustrated because she felt that no one asked Superman the type of questions that Cat was asking her, and she accidentally reveals that she and Superman are in fact cousins. After doing so, she promptly ends the interview, flying off. The next morning, Kara ate sticky buns at a cafe, with her server questioning as to how Kara could eat sticky buns for breakfast every morning, and stay as thin as she was. She was soon joined by Alex, who teased her that she liked James Olsen, after seeing how Kara had looked at him after he had stopped at their table after getting his tea. Alex emphasized to Kara that she had to stop telling people her identity as Supergirl, as the less people who knew, the better.

At CatCo Worldwide Media, Winn Schott commented on Kara revealing her relationship to Superman after the latter arrived. In an attempt to defend herself, Kara tries to argue that Grant tricked her into revealing it as she didn't mean to, before being called away by Cat herself. Walking into Cat's office, Grant announced to Kara that it was a big day for journalism, and that she had scooped The Daily Planet with revealing Supergirl and Superman's relationship. Kara however attempted to tell Cat that Supergirl might have wanted her familial connection to Superman publicly known, though to no avail. Soon after, Cat told Kara that she would be writing an expose on Supergirl for a special issue of their monthly magazine, and as such she would need bulletproof coffee, a type of coffee that improved brain energy. Finishing, Cat announced that they'd be having a big party to launch the magazine with around 1,000 guests, and she ordered Kara to move Dave to another desk, as she found his hair distracting.

At the D.E.O. Headquarters, Kara was berated by Hank Henshaw for doing the interview with Cat Grant. Afterwards, she was question by Alex as to why she did in the interview, with Kara explaining that although at first she was doing it for James, she did it for her as well, because she thought interviewing with Cat Grant would give her perspective on what being Supergirl meant. Both Kara and Alex were alerted to Agent Vasquez reporting to Henshaw about a multiple car collision on the highway. Attempting to finish his warning about giving interviews to Kara, Hank turned to find that she already had left, with Alex explaining that she was excited as it was her first car pile up. At the highway pile up, Kara landed at the scene with an injured passenger telling her that the bus driver was still inside trapped. Flying over to the bus, Kara rescued the bus driver, placing her on a nearby gurney. While being thanked by the driver, Kara was blasted backwards by a flying figure. After getting up, Kara questioned him as to his identity, with the man commenting that he was a ghost, and that he wanted Superman to suffer and lose everything, starting with Kara. After a brief battle between the two, the man flew away after his suit was damaged by Kara.

Back at the D.E.O. headquarters, Henshaw identified the man as Reactron, a villain who was at large after several public fights with Superman in the past. Kara asked Henshaw how exactly they were going to stop him, she was told by Henshaw that the D.E.O. wasn't going to help her, as Reactron was human, and as such fell out of their jurisdiction. Though she tried to argue that he could fly and shoot nuclear blasts, Alex told Kara that Reactron had simply been using bio-medical technology, which was man made. Hank finished by telling Kara that he couldn't risk exposing the D.E.O.'s existence as such, and that she should call Superman if she wanted to stop him.

At CatCo, Kara walked into Cat Grant's office, as she was putting the finishing touches on the party and needed Cat's okay on a few things. Changing the subject, Cat told Kara to have maintenance take a look at the vents, as they were emitting an incessant humming that was disrupting Cat's train of thought while she was trying to write her expose on Supergirl. Kara agreed to have them look at it, before bringing up that she needed Cat to sign off on the appetizers for tomorrow night's party. After Cat made it clear that Kara was at that point disrupting her work, Kara announced that she'd take care of it herself. Leaving the office, James questioned Kara as to whether Cat was always that tense while writing, with Kara explaining that she was. The two were then called by Winn, who told them to follow him and act natural. The three then took the elevator to Ed Flaherty's old office, with Winn explaining that since the latter had died from a heart attack behind his desk, no one wanted it, making it perfect for their base involving Supergirl related matters.

Finishing, Winn explained that he had setup the office with state of the art technology, and after being thanked by Kara, Winn moved on to the subject of Reactron. The three went over Reactron's powers and his history with Superman, with Winn telling James and Kara that he had written an algorithm that would sweep the city for any changes in radiation to potentially track down Reactron. James questioned Winn as to what they'd if they in fact found Reactron, suggesting that Kara call Superman on this particular case, as he had almost killed Superman in the past. However, Kara argued that if she did so, National City would become an easy target to every villain. She further elaborated that she was going to be defined not as Superman's cousins, but by her victories and losses, and no one elses. Meanwhile at Lord Technologies, Maxwell Lord fired an employee after he argued with him over increasing the speed to the train the company was working on. While talking with the rest of his employees, Lord was interrupted by Reactron who was seeking out someone with a background in nuclear fission. Though he attempted to abduct Carl, Lord offered himself instead.

24 hours later at CatCo, Kara and Winn watched KPJT's news report of Lord's abduction. Though Winn tried to convince Kara that it wasn't her fault, Kara told him that she had to find Maxwell Lord, though had no clue how to do so. At the same time Alex arrived offering her help, prompting the three to go down to the base Winn had setup for Supergirl operations. There, the group soon deduced the identity of Reactron, who was in fact Ben Krull, a reactor engineer of Bakerline Nuclear Power Station. Though he and his wife were thought to be dead from an attack on the Power Station by terrorists, Ben had survived the radiation, carrying a vendetta against Superman for the death of his wife. Elsewhere at the junkyard, Maxwell Lord offered to take Ben Krull back to his lab so that his team could analyze Ben's case, and he could regain a normal life. However, Ben rejected the offer and went on to order Lord to fix his suit, or the people of National City would be building memorials to him.