Winn gets beaten aiding James, leading the former to believe he is not fit for field. Kara starts investigating a strange series of missing persons. The DEO tracks the kidnappings to a fake clinical trial, which is revealed to be run by aliens. Tracking them, Kara and Mon-El pass a portal and enter the planet Maaldoria, which is the center of slave trade. Realizing that they will not have their powers due to Maaldoria's red sun, the pair tracks the kidnappees to a fortress, where they intentionally get captured and are put in the same cell as the others. They learn that Roulette is involved in the trafficking. Meanwhile, J'onn reveals that the Maaldorian atmosphere is lethal to the Martians, making Alex lead the rescue team, convincing Winn to join her. Kara incites a riot; and the prisoners lock Roulette and her Maaldorian accomplice in the cell and escape. Reuniting with the DEO, they get to the portal and return to Earth. Winn accepts his potential while Mon-El, whom the Maaldorians intentionally allowed to leave, decides to become a superhero. An alien group is revealed to be searching for Mon-El. Maggie tells Alex about her knowledge of Kara's alter ego.