Plot
 | This episode's plot summary may be too long or excessively detailed.(May 2017) |
Interviewed on an episode of The Talk , Cat speaks highly of Supergirl. At CatCo, she tasks Kara to find Winn, whom Kara sees making out with Siobhan in a storage closet. Senator Crane is impressed with Hank's leadership at the DEO and offers to provide more funding. Kara races off to assist firefighters after a satellite crashes. Suddenly, she staggers, and red glowing veins briefly appear on her face. She ignores it and flies off, not noticing the glowing red object underneath the debris.
Kara develops a more confident and abrasive attitude, leading her to upstage Siobhan when asked for a list of replacements for Lucy's position. Her behavior also affects the DEO's mission to capture a K'Hund—believing he is not worth her time, she lets him go. Alex and Hank are upset, unable to believe Kara's different behavior, but Kara angrily criticizes Hank for hiding his true identity as a Martian. Back at CatCo, Cat is growing tired of Kara's new behavior and discusses it with her. Siobhan then presents footage of Supergirl letting the K'Hund go, but Cat refuses to run the story, and asks her for more information of it. Kara discovers Siobhan has offered the story to Perry White, hoping to gain a job at the Daily Planet . She passes the information to Cat, who fires Siobhan for self-centered disloyalty.
Alex eventually captures the K'Hund, who tells Alex and Hank what really happened. That night at a club, Kara starts making advances toward James, insulting Lucy and making him uncomfortable. They are interrupted by a call from Cat, who asks James to contact Supergirl for her. After arriving at Catco, Kara dresses down Cat and throws her off the balcony, saving her at the last second to instill fear. James and Winn head to the DEO to inform Hank and Alex about Kara's strange behavior. Hank suspects she was affected by something and runs a scan that detects a form of kryptonite at the location of the fire. Maxwell Lord arrives and admits the substance was a synthetic kryptonite meant to be used against Non and his Kryptonian army. He insists that Kara's infection was accidental and offers to create an antidote. Alex confronts Kara, now clad in a Kryptonian military uniform, who pours out years of resentment on Alex before flying off.
Cat issues a public announcement denouncing Supergirl's behavior and warning people to stay away from her. Maxwell finishes the antidote and Senator Crane orders a reluctant Hank to turn Supergirl in. A DEO team confronts Kara while she is wreaking havoc in National City, but she takes everyone out. Seeing Kara about to kill Alex, Hank decides to reveal himself as a Martian to fight Kara into submission, so Alex can administer the antidote. J'onn is surrounded and Alex tells him to escape, but he reverts to Hank and surrenders to the DEO's custody. At the DEO, Kara regains consciousness and tearfully apologizes to Alex. J'onn, now imprisoned, is asked by Senator Crane about what happened to the real Hank Henshaw, but J'onn gives no answer. Alex asks J'onn why he didn't escape and he replies that he is willing to stay locked up to protect her and Kara. Kara apologizes to James, admitting to being jealous of Lucy, but James tells her he needs time to think. Supergirl then appears to Cat, expressing remorse for her actions against National City. Cat replies that winning back the city's trust will be difficult, but she has confidence Supergirl will be able to do so.
