Supergirl may be the story of one of the few surviving Kryptonians, but Martians have played a large role in the series as well. J'onn J'onzz is the last of the Green Martians, having escaped the genocide of his people by the White Martians, and he is the current head of the D.E.O., using his abilities to protect Earth from unfriendly aliens. It seems that we'll soon see J'onn take center stage on Supergirl in an episode that will likely call back to an unforgettable short story by Ray Bradbury. Actor David Harewood shared this tantalizing tease on social media:
We don't even need to see more of the episode to know that some serious trouble is heading for National City. J'onn J'onzz is no longer hiding his identity as a Martian, but he spends almost all of his time in the guise of Hank Henshaw. It looks like he'll be out in all his caped and green glory in the not-too-distant future. The episode title (as shared by David Harewood's Instagram pic) hearkens back to Ray Bradbury's classic sci-fi story The Martian Chronicles, and we can bet that the connection means bad things are coming for J'onn.
The Martian Chronicles follows humanity fleeing from an Earth that has been destroyed by nuclear war, and the survivors travel out to Mars to occupy the planet. The native Martians are nearly all killed by a disease transmitted to them by a human scouting expedition, and Mars becomes a sort of second Earth, where the humans are poised to become the new Martians by the end of the story.
The parallels between J'onn J'onnz' story of what happened to the Green Martians on Supergirl and what happened to the Martians in The Martian Chronicles are pretty clear. Like the humans of Ray Bradbury's tale were invaders who destroyed the population of Mars, the White Martians of Supergirl emerged from their subterranean habitat to wipe out the Green Martians and take over the planet. Of course, the humans of The Martian Chronicles didn't intentionally kill off the Martians, whereas the White Martians deliberately slaughtered almost the entire race of Green Martians, so there are some key differences.
The episode description for "The Martian Chronicles" reveals that a White Martian will visit National City to take M'gann M'orzz - also known as Miss Martian - back to Mars to be punished for betraying the other White Martians. The good guys will have to come up with a plan to combat the shape-shifting bad guy before he can do the kind of damage to Earth that he and the White Martians did to Mars.