Last night's Season 3 finale of Supergirl ended with quite the shocker, with the reveal that a powerful rock had created another version of Kara Zor-El. This doppelganger was glimpsed very briefly, amid a snowstorm in the middle of Sibera where she was discovered by Russian soldiers.
All signs seem to point at the fact that this second Supergirl will serve as the next season's main villain. But we already have more than a clue as to what the story of Season 4 will look like: apparently, it will take a cue from the beloved DC Elseworlds story Superman: Red Son.
In an interview with TVLine, executive producers Robert Rovner and Jessica Queller revealed the comic book inspiration behind Season 4. "For fans of the comics, I think they might recognize that the story we want to tell is inspired by the iconic DC Comics’ Red Son, which told an alternate origin story for Superman," Rovner said.
Written by Mark Millar and illustrated by Dave Johnson and Kilian Plunkett, Superman: Red Son explored the origin story of Superman through a different lens: in this alternate reality story, the rocket carrying baby Kal-El did not land in the United States, but Russia instead. Superman grew up to become Russia's enforcer instead of America's champion.
Therefore, it appears as if Kara's new doppelganger will side with the government of the Russian soldiers who found her, making her a direct and opposite threat to National City's Supergirl.
Returning to The CW this fall, Supergirl stars Melissa Benoist as the Girl of Steel, David Harewood as Martian Manhunter, Mehcad Brooks as Jimmy Olsen, Chyler Leigh as Alex Danvers and Jeremy Jordan as Winn Schott, with appearances by Calista Flockhart as Cat Grant and Tyler Hoechlin as Superman.